Notch Signaling in Embryology and Cancer: Notch Signaling in Cancer [1st ed.] 9783030550301, 9783030550318

This thoroughly revised second edition is an up-to-date overview of the current knowledge of Notch and Notch signaling i

251 88 8MB

English Pages XVII, 228 [240] Year 2021

Report DMCA / Copyright


Polecaj historie

Notch Signaling in Embryology and Cancer: Notch Signaling in Cancer [1st ed.]
 9783030550301, 9783030550318

Table of contents :
Front Matter ....Pages i-xvii
Notch Signaling in Prevention And Therapy: Fighting Cancer with a Two-Sided Sword (Jörg Reichrath, Sandra Reichrath)....Pages 1-7
Transcription Factor RBPJ as a Molecular Switch in Regulating the Notch Response (Benedetto Daniele Giaimo, Ellen K. Gagliani, Rhett A. Kovall, Tilman Borggrefe)....Pages 9-30
Unravelling of Hidden Secrets: The Tumour Suppressor Lethal (2) Giant Discs (Lgd)/CC2D1, Notch Signalling and Cancer (Tobias Reiff, Miriam Baeumers, Christine Tibbe, Thomas Klein)....Pages 31-46
Notch and Endometrial Cancer (Violeta Jonusiene, Ausra Sasnauskiene)....Pages 47-57
NOTCH and Esophageal Squamous Cell Carcinoma (Yong Li, Yahui Li, Xiaoxin Chen)....Pages 59-68
Notch Signaling and Liver Cancer (Kazunori Kawaguchi, Shuichi Kaneko)....Pages 69-80
Notch in Head and Neck Cancer (Cristina Porcheri, Thimios A. Mitsiadis)....Pages 81-103
Notch Signaling and Human Papillomavirus–Associated Oral Tumorigenesis (Trinath Das, Rong Zhong, Michael T. Spiotto)....Pages 105-122
The Impact of Notch Signaling for Carcinogenesis and Progression of Nonmelanoma Skin Cancer: Lessons Learned from Cancer Stem Cells, Tumor Angiogenesis, and Beyond (Jörg Reichrath, Sandra Reichrath)....Pages 123-154
Notch Signaling in Thyroid Cancer (Rachael Guenter, Zeelu Patel, Herbert Chen)....Pages 155-168
The Relevance of Notch Signaling in Cancer Progression (Fasoulakis Zacharias, Daskalakis George, Theodora Marianna, Antsaklis Panos, Sindos Michael, Diakosavvas Michail et al.)....Pages 169-181
Notch Signaling and the Breast Cancer Microenvironment (Qiang Shen, Michael Reedijk)....Pages 183-200
Notch Pathway: A Journey from Notching Phenotypes to Cancer Immunotherapy (Giulia Monticone, Lucio Miele)....Pages 201-222
Correction to: Notch Signaling and Human Papillomavirus–Associated Oral Tumorigenesis (Trinath Das, Rong Zhong, Michael T. Spiotto)....Pages C1-C1
Back Matter ....Pages 223-228

Citation preview

Advances in Experimental Medicine and Biology 1287

Jörg Reichrath Sandra Reichrath  Editors

Notch Signaling in Embryology and Cancer Notch Signaling in Cancer

Advances in Experimental Medicine and Biology Volume 1287 Series Editors Wim E. Crusio, Institut de Neurosciences Cognitives et Intégratives d’Aquitaine, CNRS and University of Bordeaux UMR 5287, Pessac Cedex, France Haidong Dong, Departments of Urology and Immunology, Mayo Clinic, Rochester, MN, USA Heinfried H. Radeke, Institute of Pharmacology & Toxicology, Clinic of the Goethe University Frankfurt Main, Frankfurt am Main, Hessen, Germany Nima Rezaei, Research Center for Immunodeficiencies, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran Junjie Xiao, Cardiac Regeneration and Ageing Lab, Institute of Cardiovascular Sciences, School of Life Science, Shanghai University, Shanghai, China

Advances in Experimental Medicine and Biology provides a platform for scientific contributions in the main disciplines of the biomedicine and the life sciences. This series publishes thematic volumes on contemporary research in the areas of microbiology, immunology, neurosciences, biochemistry, biomedical engineering, genetics, physiology, and cancer research. Covering emerging topics and techniques in basic and clinical science, it brings together clinicians and researchers from various fields. Advances in Experimental Medicine and Biology has been publishing exceptional works in the field for over 40 years, and is indexed in SCOPUS, Medline (PubMed), Journal Citation Reports/Science Edition, Science Citation Index Expanded (SciSearch, Web of Science), EMBASE, BIOSIS, Reaxys, EMBiology, the Chemical Abstracts Service (CAS), and Pathway Studio. 2019 Impact Factor: 2.450 5 Year Impact Factor: 2.324 More information about this series at

Jörg Reichrath  •  Sandra Reichrath Editors

Notch Signaling in Embryology and Cancer Notch Signaling in Cancer

Editors Jörg Reichrath Department of Dermatology Saarland University Medical Center Homburg, Saarland, Germany

Sandra Reichrath Department of Dermatology Saarland University Medical Center Homburg, Saarland, Germany School of Health Professions

Saarland University Medical Center Homburg, Saarland, Germany

ISSN 0065-2598     ISSN 2214-8019 (electronic) Advances in Experimental Medicine and Biology ISBN 978-3-030-55030-1    ISBN 978-3-030-55031-8 (eBook) © Springer Nature Switzerland AG 2021 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors, and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, expressed or implied, with respect to the material contained herein or for any errors or omissions that may have been made. The publisher remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. This Springer imprint is published by the registered company Springer Nature Switzerland AG The registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

We dedicate this book to our sons, Benjamin and Niklas, the absolute joy of our lives


Notch and Cancer: Lessons Learned from Failure – or on the Long and Winding Road from John S.  Dexter’s mutant Fruit Flies to Synthetic Notch Receptors, and beyond This book was motivated by the desire we and others have to further the evolution of the many fascinating facets of Notch’s role for biology and medicine. To stimulate the interest of potential readers, this preface has several purposes, which include providing some brief information (a) concerning its content with a focus on potential future developments, (b) how the book came about, and (c) acknowledging the long list of authors and other individuals who helped move forward this project. The success of the first edition of Notch Signaling in Embryology and Cancer, which was published by Landes and Springer in 2012 in the prestigious series Advances in Experimental Medicine and Biology (Reichrath and Reichrath 2012), clearly indicated that this text met an important need in this exciting field. It was a benchmark in its field, fulfilling the need to provide a broad audience (ranging from medical students to basic scientists, physicians and all other health care professionals) with up-to-date information in a comprehensive, highly readable format, with individual chapters written by highly respected experts. We were aware from the beginning that undertaking the first edition would include a commitment to producing a second one. The enormous advances that have been made in recent years on this topic, moving forward at a dizzying pace, now clearly justify the need for a second edition. We decided to publish this updated and extended new edition as three separate volumes, featuring chapters written by both new and returning authors, to add to the content of the first edition. Each volume contains a separate table of contents and full index to help the reader find specific information. In the different volumes of Notch Signaling in Embryology and Cancer, leading experts in the field present a comprehensive, highly readable overview on selected aspects of three important topics related to Notch signaling, namely the underlying molecular mechanisms that mediate its biological effects (Volume I) (Reichrath and Reichrath 2020a) (adding to the recent important book publication on this topic from Tilman Borggrefe and Benedetto Daniele Giaimo; Borggrefe and Giaimo 2018), its role in embryogenesis (Volume II) (Reichrath and Reichrath 2020b), and last but not least its relevance for pathogenesis, progression, and therapy of



cancer (Volume III) (Reichrath and Reichrath 2020c). This third volume of Notch Signaling in Embryology and Cancer summarizes the fascinating role of this pathway, which first developed during evolution in metazoans and was first discovered in the fruit fly drosophila melanogaster, for cancer (Reichrath and Reichrath 2020c). When the American scientist John S. Dexter published in 1914 the characteristic notched-wing phenotype (a nick or notch in the wingtip that earned the mutant gene the name Notch) that he had recognized in mutant fruit flies (drosophila melanogaster), he couldn’t have expected the tremendous impact that this finding would later have for cancer and many other fields in biology and medicine. This thoughtful observation made in his research laboratory at Olivet College (Olivet, Michigan, USA) opened many fascinating avenues for a better understanding of carcinogenesis and for the development of promising new anti-cancer therapeutics that target Notch signaling pharmacologically. During the last decades, a great deal of impressive scientific progress has demonstrated that Notch signaling represents a master pathway involved in carcinogenesis and cancer progression, with many types of cancer having been found to contain Notch mutations. On a first look, the Notch pathway, which governs in oncology so many key cell fate decisions and other cellular core processes, seems phantasmally simple, because a direct link between an extracellular signal and transcriptional output without the requirement of an extended chain of protein intermediaries (as needed by so many other signaling pathways) represents one of its key features (Reichrath and Reichrath 2020a, b). However, on a second, closer look, this obvious simplicity hides remarkable complexity and, consistent with its central role in many aspects of development, adult tissue homeostasis, and cancer, it can be recognized that Notch signaling depends on an extensive collection of mechanisms that it employs alongside of its core transcriptional machinery. It has to be noted that many early attempts to target Notch signaling for cancer treatment represented major setbacks, since they did not lead as expected to good clinical response rates. Notch antagonistic antibodies and gamma secretase inhibitors (GSI) may serve here as examples, showing promising results in preclinical studies but disappointing results in clinical trials. However, our understanding of the molecular biology of Notch signaling has now opened exciting perspectives to overcome these obstacles. Giulia Monticone and Lucio Miele discuss elsewhere in this book (Monticone and Miele 2020), in their direction-defining contribution, which reflects the outstanding expertise of the authors, current and new Notch-­ targeting therapies with their exciting promises and challenges. As these authors explain, targeting Notch allows to virtually modulate any aspect of cancer. However, this means that Notch-targeting must be highly specific toward the desired target and it seems that we at present still have not unraveled all the secrets and potentials of this pathway (Monticone and Miele 2020). In this context, Notch pleiotropic nature seems to be both the advantage and the challenge of Notch-targeted therapies (Monticone and Miele 2020). The accumulated knowledge about the molecular biology of Notch signaling in individual types of cancer, for example, whether Notch muta-




tions detected in cancer are assumed to be loss or gain of function depending on whether Notch is tumor suppressor or oncogenic, respectively, provides chances for improvements, for it may be possible to identify responder patients depending on molecular signatures detected in tumors (Monticone and Miele 2020). It is now becoming evident that while the first Notch-­targeted therapies were designed to inhibit Notch, in certain situations Notch signaling should be promoted instead of inhibited (Monticone and Miele 2020). Recent investigations on Notch regulation have revealed many alternative ways in which Notch can be activated or inhibited, which involve the extensive collection of mechanisms that Notch employs alongside of its core transcriptional machinery. Other mechanisms that can be used as therapeutical targets include the ubiquitination of Notch mediated by different ubiquitin ligases that orchestrate the degradation and the ligand-independent activation of Notch. Moreover, Notch’s roles for microenvironment and for metabolism reprogramming (now considered as a major hallmark of cancer, through which cancer cells can adapt and survive different environmental changes, develop resistance to treatments, and modulate anti-tumor immunity) of many tumor types may represent targets for anti-cancer treatment (Monticone and Miele 2020). Understanding whether Notch function is pro- or anti-­tumoral is essential, especially because Notch is differentially expressed in subsets of cells within the tumor and its microenvironment including tumor-­infiltrating immune cells (Monticone and Miele 2020). Notch is heavily involved in shaping the immune system in physiological conditions and the pro-tumoral immune microenvironment in cancer (Monticone and Miele 2020), providing a strong rational for the evaluation of Notch-targeting strategies as immunomodulators (Monticone and Miele 2020). The promises associated with the many fascinating facets of targeting Notch signaling for cancer treatment include the generation of synthetic Notch receptors, called synNotches, which have customizable extracellular and intracellular domains linked by the transmembrane domain of Notch, thus allowing customizable extra to intracellular signaling. In conclusion, a more rational use of Notch-­targeting therapeutics should be highly specific, taking into account many aspects, including the tumor type, patient responders, Notch alterations, “off targets,” and potential combinatorial treatments. Understanding the precise mechanism by which Notch is modulated in different sets of cells within the tumor or its microenvironment including immune cells will be crucial to predict whether Notch-targeting therapies will be effective and to identify new druggable targets (Monticone and Miele 2020). Therefore, a patientbased, mechanistic-based use of Notch-targeting therapies is urgently needed. The individual chapters of this book give an up-to-date overview on selected aspects of our present understanding of Notch’s role in cancer. We have enjoyed very much the task of bringing this second edition to you. We are convinced that it will be as successful as the previous edition. We are indebted to our many authors and are very grateful for their willingness to contribute to this book. We would also like to express our thanks to Murugesan Tamilselvan, Anthony Dunlap, Larissa Albright, and all the



other members of Springer’s staff for their expertise, diligence, and patience in helping us complete this book. Enjoy the reading!

Homburg, Saarland, Germany

Sandra Reichrath Jörg Reichrath

References Borggrefe T, Giaimo BD (eds) (2018) Molecular mechanisms of notch signaling. Adv Exp Med Biol 1066:1–394 Dexter JS (1914) The analysis of a case of continuous variation in drosophila by a study of its linkage relations. Am Nat 48:712–758 Monticone G, Miele L (2020) Notch pathway: a journey from notching phenotypes to cancer immunotherapy. Adv Exp Med Biol 1287:201–222 Reichrath J, Reichrath S (eds) (2012) Notch signaling in embryology and cancer. Adv Exp Med Biol 727:1–320 Reichrath J, Reichrath S (eds) (2020a) Notch signaling in embryology and cancer (Vol. I). Molecular biology of notch signaling. Adv Exp Med Biol 1227:1–164 Reichrath J, Reichrath S (eds) (2020b) Notch signaling in embryology and cancer (Vol. II). Notch signaling in embryology. Adv Exp Med Biol 1218:1–188 Reichrath J, Reichrath S (eds) (2020c) Notch signaling in embryology and cancer (Vol. III). Notch signaling in cancer. Adv Exp Med Biol 1287:1–222


1 Notch Signaling in Prevention And Therapy: Fighting Cancer with a Two-Sided Sword����������������������������������������������������   1 Jörg Reichrath and Sandra Reichrath 2 Transcription Factor RBPJ as a Molecular Switch in Regulating the Notch Response��������������������������������������������������   9 Benedetto Daniele Giaimo, Ellen K. Gagliani, Rhett A. Kovall, and Tilman Borggrefe 3 Unravelling of Hidden Secrets: The Tumour Suppressor Lethal (2) Giant Discs (Lgd)/CC2D1, Notch Signalling and Cancer����������������������������������������������������������������������������������������  31 Tobias Reiff, Miriam Baeumers, Christine Tibbe, and Thomas Klein 4 Notch and Endometrial Cancer������������������������������������������������������  47 Violeta Jonusiene and Ausra Sasnauskiene 5 NOTCH and Esophageal Squamous Cell Carcinoma������������������  59 Yong Li, Yahui Li, and Xiaoxin Chen 6 Notch Signaling and Liver Cancer ������������������������������������������������  69 Kazunori Kawaguchi and Shuichi Kaneko 7 Notch in Head and Neck Cancer����������������������������������������������������  81 Cristina Porcheri and Thimios A. Mitsiadis 8 Notch Signaling and Human Papillomavirus–Associated Oral Tumorigenesis�������������������������������������������������������������������������� 105 Trianth Das, Rong Zhong, and Michael T. Spiotto 9 The Impact of Notch Signaling for Carcinogenesis and Progression of Nonmelanoma Skin Cancer: Lessons Learned from Cancer Stem Cells, Tumor Angiogenesis, and Beyond�������������������������������������������������� 123 Jörg Reichrath and Sandra Reichrath 10 Notch Signaling in Thyroid Cancer������������������������������������������������ 155 Rachael Guenter, Zeelu Patel, and Herbert Chen



11 The Relevance of Notch Signaling in Cancer Progression ���������� 169 Zacharias Fasoulakis, George Daskalakis, Marianna Theodora, Panos Antsaklis, Michael Sindos, Michail Diakosavvas, Kyveli Angelou, Dimitrios Loutradis, and Emmanuel N. Kontomanolis 12 Notch Signaling and the Breast Cancer Microenvironment�������� 183 Qiang Shen and Michael Reedijk 13 Notch Pathway: A Journey from Notching Phenotypes to Cancer Immunotherapy�������������������������������������������������������������� 201 Giulia Monticone and Lucio Miele Index������������������������������������������������������������������������������������������������������  223



Kyveli  Angelou National and Kapodistrian University of Athens  – 1st Department of Obstetrics and Gynecology, Athens, Greece Panos  Antsaklis National and Kapodistrian University of Athens  – 1st Department of Obstetrics and Gynecology, Athens, Greece Miriam  Baeumers Institut fuer Genetik, Heinrich-Heine-Universitaet Duesseldorf, Duesseldorf, Germany Tilman Borggrefe  Institute of Biochemistry, University of Giessen, Giessen, Germany Herbert  Chen Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA Xiaoxin Chen  Cancer Research Program, Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA Center for Gastrointestinal Biology and Disease, Division of Gastroenterology and Hepatology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA Trianth Das  Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL, USA George  Daskalakis  National and Kapodistrian University of Athens  – 1st Department of Obstetrics and Gynecology, Athens, Greece Michail Diakosavvas  National and Kapodistrian University of Athens – 1st Department of Obstetrics and Gynecology, Athens, Greece Zacharias Fasoulakis  National and Kapodistrian University of Athens – 1st Department of Obstetrics and Gynecology, Athens, Greece Ellen  K.  Gagliani Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA Benedetto Daniele Giaimo  Institute of Biochemistry, University of Giessen, Giessen, Germany




Rachael  Guenter Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA Violeta  Jonusiene Vilnius University, Life Sciences Center, Institute of Biosciences, Vilnius, Lithuania Shuichi  Kaneko Department of Gastroenterology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan Kazunori  Kawaguchi  Department of Gastroenterology, Kanazawa University Graduate School of Medical Sciences, Kanazawa, Japan Thomas  Klein  Institut fuer Genetik, Duesseldorf, Duesseldorf, Germany


Emmanuel  N.  Kontomanolis Democritus University of Thrace  – Department of Obstetrics and Gynecology, Alexandroupolis, Greece Rhett  A.  Kovall Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA Yahui  Li Cancer Research Program, Julius L.  Chambers Biomedical Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA Yong Li  Department of Thoracic Surgery, National Cancer Center, Cancer Hospital of Chinese Academy of Medical Sciences, Beijing, China Cancer Research Program, Julius L.  Chambers Biomedical Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA Dimitrios Loutradis  National and Kapodistrian University of Athens – 1st Department of Obstetrics and Gynecology, Athens, Greece Lucio Miele  Department of Genetics and Louisiana Cancer Research Center, Louisiana State University Health Sciences Center, New Orleans, LA, USA Thimios A. Mitsiadis  Institute of Oral Biology, Orofacial Development and Regeneration, University of Zurich, Zurich, Switzerland Giulia Monticone  Department of Genetics and Louisiana Cancer Research Center, Louisiana State University Health Sciences Center, New Orleans, LA, USA Zeelu Patel  Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA Cristina  Porcheri Institute of Oral Biology, Orofacial Development and Regeneration, University of Zurich, Zurich, Switzerland Michael  Reedijk Department of Surgical Oncology, Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada



Jörg Reichrath  Department of Dermatology, Saarland University Medical Center, Homburg, Germany Sandra  Reichrath Department of Dermatology, Saarland University Medical Center, Homburg, Germany School of Health Professions, Saarland University Medical Center, Homburg, Germany Tobias Reiff  Institut fuer Genetik, Heinrich-Heine-Universitaet Duesseldorf, Duesseldorf, Germany Ausra  Sasnauskiene Vilnius University, Life Sciences Center, Institute of Biosciences, Vilnius, Lithuania Qiang  Shen  Department of Surgical Oncology, Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada Michael  Sindos National and Kapodistrian University of Athens  – 1st Department of Obstetrics and Gynecology, Athens, Greece Michael  T.  Spiotto Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL, USA Department of Radiation Oncology, The University of Texas M.D. Anderson Cancer Center, Houston, TX, USA Marianna Theodora  National and Kapodistrian University of Athens – 1st Department of Obstetrics and Gynecology, Athens, Greece Christine  Tibbe  Institut fuer Genetik, Duesseldorf, Duesseldorf, Germany


Rong Zhong  Department of Radiation and Cellular Oncology, University of Chicago, Chicago, IL, USA

About the Editors

Jörg  Reichrath  is Professor of Dermatology and Deputy Director of the Clinic for Dermatology, Allergology and Venerology at Saarland University Medical Center in Homburg, Germany. Professor Reichrath has received his academic degrees (Dr. med.) from Saarland University, Germany. His research interests include photobiology, dermato-endocrinology, and dermato-­oncology. He is a member of numerous national and international scientific organizations, including the German Dermatological Society (DDG), the Deutsche Krebsgesellschaft (DKG), the German Dermatologic Cooperative Oncology Group (DeCOG), the Arbeitsgemeinschaft Dermatologische Forschung (ADF), and the Deutsche Akademie für Photobiologie und Phototechnologie e. V. (DAFP). He has been awarded numerous prizes including the Arnold Rikli-Prize. Sandra  Reichrath  is Researcher and Scientist at the Clinic for Dermatology, Allergology and Venerology, Saarland University Medical Center Hospital, in Homberg, Germany, where she works at present in the School of Health Professions. Sandra received her academic degrees from the Faculty of Biology at AlbertLudwig-University, Freiburg, Germany. Her research interests include Notch signaling in glioblastoma and skin tumors.



Notch Signaling in Prevention And Therapy: Fighting Cancer with a Two-Sided Sword Jörg Reichrath and Sandra Reichrath


The evolutionary conserved Notch pathway that first developed in metazoans and that was first discovered in fruit flies (Drosophila melanogaster) governs fundamental cell fate decisions and many other cellular key processes not only in embryonic development but also during initiation, promotion, and progression of cancer. On a first look, the Notch pathway appears remarkably simple, with its key feature representing a direct connection between an extracellular signal and transcriptional output without the need of a long chain of protein intermediaries as known from many other signaling pathways. However, on a second, closer look, this obvious simplicity exerts surprising complexity. There is no doubt that the enormous scientific progress in unraveling the functional mechanisms that underlie this complexity has recently greatly increased our knowledge about the role of Notch signaling

J. Reichrath (*) Department of Dermatology, Saarland University Medical Center, Homburg, Germany e-mail: [email protected] S. Reichrath Department of Dermatology, Saarland University Medical Center, Homburg, Germany School of Health Professions, Saarland University Medical Center, Homburg, Germany

for pathogenesis and progression of many types of cancer. Moreover, these new scientific findings have shown promise in opening new avenues for cancer prevention and therapy, although this goal is still challenging. Vol. III of the second edition of the book Notch Signaling in Embryology and Cancer, entitled Notch Signaling in Cancer, summarizes important recent developments in this fast-­ moving and fascinating field. Here, we give an introduction to this book and a short summary of the individual chapters that are written by leading scientists, covering the latest developments in this intriguing research area. Keywords

Angiogenesis · Cancer · Cancer stem cells · Cancer treatment · Notch · Non-melanoma skin cancer · Notch signaling · Notch pathway · Skin cancer · Tumor angiogenesis

Abbreviations BCC Basal cell carcinoma CSC Cancer stem cell Dll Delta-like ESCC Esophageal squamous carcinoma Hes Hairy and enhancer of split

© Springer Nature Switzerland AG 2021 J. Reichrath, S. Reichrath (eds.), Notch Signaling in Embryology and Cancer, Advances in Experimental Medicine and Biology 1287,




HNSCCs Head and neck squamous cell cancers HPV Human papillomavirus Hrt Hes-related transcription factor JAG Jagged NID Notch intracellular domain NMSC Non-melanoma skin cancer SCC Squamous cell carcinoma

Evolutionary conserved Notch signaling that first developed in metazoans (Gazave et  al. 2009; Richards and Degnan 2009) and that was first discovered in the fruit fly Drosophila melanogaster represents one of the most fascinating pathways that govern both embryonic development and adult tissue homeostasis and an essential element of the defense line against cancer. Notably, the fascinating tale that earned the gene the name Notch began over a century ago, when the American scientist John S. Dexter discovered at Olivet College (Olivet, Michigan, USA) the typical notched-wing phenotype (a nick or notch in the wingtip) in his stock of mutant fruit flies Drosophila melanogaster (Dexter 2014; Reichrath and Reichrath 2020a, b). The alleles responsible for this phenotype were identified 3 years later at Columbia University (New York City, New York, USA) by another American scientist, Thomas Hunt Morgan (1866–1945) (Morgan 1917; Reichrath and Reichrath 2020a, b). In the following years, many additional alleles were identified that were associated with the Notch phenotype (Morgan 1928; Reichrath and Reichrath 2020a, b). In subsequent decades, notwithstanding the extensive research on the Notch locus, researchers struggled to identify the function for the Notch gene due to the lethality early in embryogenesis and the broad variety of phenotypic consequences of Notch mutants ­ (Reichrath and Reichrath 2020a, b). Despite these challenges, the observations of John S. Dexter, Thomas Hunt Morgan, and others were finally confirmed by cloning and sequencing of the mutant Notch locus in the research laboratories of Spyros Artavanis-Tsakonas and Michael W.  Young, more than half a century later

J. Reichrath and S. Reichrath

(Wharton et al. 1985; Kidd et al. 1986). A huge mountain of new scientific evidence, which has been constantly growing during the last decades, has now convincingly shown that the Notch pathway governs, from sponges, roundworms, Drosophila melanogaster, and mice to humans, many key cell fate decisions and other core processes that are of high importance both for embryogenesis and in adult tissues (Andersson et al. 2011). Moreover, it has now been demonstrated that Notch signaling represents in humans an essential element of the defense line against cancer. In 2012, when the first edition of Notch Signaling in Embryology and Cancer was published by Landes and Springer in the prestigious series Advances in Experimental Medicine and Biology, it was the benchmark on this topic, providing a broad audience (ranging from medical students to basic scientists, physicians, and all other healthcare professionals) with up-to-date information in a comprehensive, highly readable format. Since that time, a huge mountain of new scientific findings has been built up that underlines the many facets and the high biological/ clinical relevance of Notch signaling for health and many diseases, including various types of cancer (Reichrath and Reichrath 2020a, b). Therefore, we decided that it is now the right time to publish an updated and extended version. The second edition of this book has been expanded substantially to cover all aspects of this fast-growing field and has been divided into three separate volumes to include additional chapters (Reichrath and Reichrath 2020a, b). In this new edition, leading scientists provide a comprehensive, highly readable overview on molecular mechanisms of Notch signaling (Volume I), Notch’s role in embryonic development (Volume II), and, last but not least, its relevance for cancer (Volume III) (Reichrath and Reichrath 2020a, b). This third volume gives an overview on Notch’s role for selected types of cancer. As outlined previously, it must be emphasized that the Notch pathway seems delusorily simple, with one of its key features being a direct link between an extracellular signal and transcriptional output without the requirement for an extended chain of

1  Notch Signaling in Prevention And Therapy: Fighting Cancer with a Two-Sided Sword

protein intermediaries as needed by so many other signaling pathways (Hunter and Giniger 2020; Reichrath and Reichrath 2020a, b). However, this apparent simplicity hides remarkable complexity, and, consistent with its important role in many aspects of development, it has to be noted that Notch signaling has an extensive collection of mechanisms that it exerts alongside of its core transcriptional machinery (Hunter and Giniger 2020; Reichrath and Reichrath 2020a, b). In many biological processes, including morphological events during pathogenesis and progression of cancer, Notch-mediated coordination of the activity of gene expression with regulation of cell morphology is of high importance (Hunter and Giniger 2020; Reichrath and Reichrath 2020a, b). Fortunately, the generation and investigation of knockout mice and other animal models have in recent years resulted in a huge mountain of new informations concerning Notch gene function, allowing to dissect the role of specific Notch components in human development and disease. This volume is intended to provide both basic scientists and clinicians who seek today’s clearest understanding of the molecular mechanisms that mediate Notch signaling with an authoritative day-to-day source. In the first chapter, Benedetto Daniele Giaimo, Ellen Kolb, Rhett A.  Kovall, and Tilman Borggrefe convincingly demonstrate the importance of the transcription factor RBP-J as a molecular switch in regulating the Notch response (Benedetto Daniele Giaimo et al. 2020). As they explain, the Notch signal transduction cascade requires cell-to-cell contact and results in the proteolytic processing of the Notch receptor and subsequent assembly of a transcriptional coactivator complex containing the Notch intracellular domain (NID) and transcription factor RBP-J. In the absence of a Notch signal, RBP-J remains at Notch target genes and dampens transcriptional output. Like in other signaling pathways, RBP-J is able to switch from activation to repression by associating with corepressor complexes containing several chromatin-modifying enzymes. In their chapter, Giaimo et  al. focus on the recent advances concerning RBP-J corepressor functions, especially in regard to chromatin regula-


tion. The authors put this into the context of one of the best-studied model systems for Notch, blood cell development. They elaborate that alterations in the RBP-J corepressor functions can contribute to the development of leukemia, especially in the case of acute myeloid leukemia (AML). The versatile role of transcription factor RBP-J in regulating pivotal target genes like c-MYC and HES1 may contribute to the better understanding of the development of leukemia. In the following chapter, Tobias Reiff, Miriam Baeumers, Christine Tibbe, and Thomas Klein provide a review on the role of the tumor suppressor lethal (2) giant discs (Lgd)/CC2D1, Notch signaling, and cancer (Reiff et  al. 2020). They state that the endosomal pathway plays a pivotal role upon signal transduction in the Notch pathway and that recent work on lethal (2) giant discs (lgd) points to an additional critical role in avoiding uncontrolled ligand-independent signaling during trafficking of the Notch receptor through the endosomal pathway to the lysosome for degradation. In their chapter, the authors line out the fascinating journey of Notch through the endosomal system and present an overview of the current knowledge about Lgd and its mammalian orthologs Lgd1/CC2D1b and Lgd2/CC2D1a. They further discuss how Notch is activated in the absence of lgd function in Drosophila and ask whether there is evidence that a similar ligand-­ independent activation of the Notch pathway can also happen in mammals if the orthologs are inactivated. In the next chapter, Violeta Jonusiene and Ausra Sasnauskiene summarize the relevance of Notch for endometrial cancer (Jonusiene and Sasnauskiene 2020). They explain that human endometrium is a unique, highly dynamic tissue that undergoes cyclic changes of cell proliferation, differentiation, and death. Endometrial cancer is the most common malignancy among women in developed countries. Importantly, the incidence of endometrial cancer is rising in high-­ income countries. Currently histological classification is used for subtyping of endometrial cancer, while ongoing research is evaluating markers for more accurate molecular classification. As the authors point out, accumulating evi-


dence links aberrant Notch signaling with diseases such as hyperplasia and endometrial cancer. This chapter summarizes the current state of Notch signaling investigations in the endometrium, endometriosis, and endometrial cancer. In the following chapter, Yong Li, Yahui Li, and Xiaoxin Chen review our scientific knowledge of Notch’s role in esophageal squamous cell carcinoma (ESCC) (Li et al. 2020). The authors explain that ESCC is a deadly disease that requires extensive research on its mechanisms, prevention, and therapy. Recent studies have shown that NOTCH mutations are commonly seen in human ESCC. This chapter summarizes our current understanding of the Notch pathway in normal esophagus and in ESCC. The authors explain that in normal esophagus, Notch pathway regulates the development of esophageal squamous epithelium, in particular, squamous differentiation. Exposure to extrinsic and intrinsic factors, such as gastroesophageal reflux, alcohol drinking, and inflammation, downregulates the Notch pathway and thus inhibits squamous differentiation of esophageal squamous epithelial cells. In ESCC, Notch plays a dual role as both a tumor suppressor pathway and an oncogenic pathway. In summary, further studies are warranted to develop Notch activators for the prevention of ESCC and Notch inhibitors for targeted therapy of a subset of ESCC with activated Notch pathway. In the next chapter, Kazunori Kawaguchi and Shuichi Kaneko report on the relevance of Notch signaling for liver cancer (Kawaguchi and Kaneko 2020). They point out that interactions between liver cells are closely regulated by Notch signaling. Notch signaling has been reported clinically related to bile duct hypogenesis in Alagille syndrome, which is caused by mutations in the Jagged1 gene. Notch activation and hepatocarcinogenesis are closely associated since cancer signaling is affected by the development of liver cells and cancer stem cells. Gene expression and genomic analysis using a microarray revealed that abnormalities in Notch-related genes were associated with the aggressiveness of liver cancer. This pattern was also accompanied

J. Reichrath and S. Reichrath

with α-fetoprotein- and EpCAM-expressing phenotypes in vitro, in vivo, and in clinical tissues. Hepatitis B or C virus chronic infection or alcohol- or steatosis-related liver fibrosis induces liver cancer. Previous reports demonstrated that HBx, a hepatitis B virus protein, was associated with Jagged1 expression. The authors report their finding that the Jagged1 and Notch1 signaling pathways were closely associated with the transcription of covalently closed circular hepatitis B virus DNA, which regulated cAMP response element-binding protein, thereby affecting Notch1 regulation by the E3 ubiquitin ligase ITCH.  This viral pathogenesis in hepatocytes induces liver cancer. The authors conclude that Notch signaling exerts various actions and is a clinical signature associated with hepatocarcinogenesis and liver context-related developmental function. In the next contribution, Cristina Porcheri and Thimios A.  Mitsiadis report on Notch’s role in head and neck cancer (Porcheri and Mitsiadis 2020). Head and neck cancer is a group of neoplastic diseases affecting the facial, oral, and neck region. It is one of the most common cancers worldwide with an aggressive, invasive evolution in the late stages of malignancy. Due to the heterogeneity of the tissues affected, it is particularly challenging to study the molecular mechanisms at the basis of these tumors, and to date we are still lacking accurate targets for prevention and therapy. The authors explain that Notch signaling is involved in a variety of tumorigenic mechanisms, such as regulation of the tumor microenvironment, cell-to-cell communication, and metabolic homeostasis. Moreover, they provide an up-to-date review of the role of Notch in head and neck cancer and draw parallels with other types of solid tumors where the Notch pathway plays a crucial role in emergence, maintenance, and progression of the disease. Additionally, the authors give a perspective view on the importance of the pathway in neoplastic development in order to define future lines of research and novel therapeutic approaches. In the following chapter, Trianth Das, Rong Zhong, and Michael T. Spiotto explain the rele-

1  Notch Signaling in Prevention And Therapy: Fighting Cancer with a Two-Sided Sword

vance of Notch signaling for human papillomavirus-­ associated oral tumorigenesis (Das et al. 2020). They point out that the Notch pathway is critical for the development of many cell types including the squamous epithelium lining of cutaneous and mucosal surfaces. In genetically engineered mouse models, Notch1 acts as one of the first steps to commit basal keratinocytes to terminally differentiate. Similarly, in human head and neck squamous cell cancers (HNSCCs), Notch1 is often lost consistent with its essential tumor-suppressive role for initiating keratinocyte differentiation. However, constitutive Notch1 activity in the epithelium results in expansion of the spinous keratinocyte layers and impaired terminal differentiation which is consistent with the role of Notch1 as an oncogene in other cancers, especially T-cell acute lymphoblastic leukemia. The authors also report their previous observation that Notch1 plays a dual role as both a tumor suppressor and oncogene depending on the mutational context of the tumor. Namely, gain or loss or Notch1 activity promoted the development of human papillomavirus (HPV)-associated cancers. The additional HPV oncogenes likely disrupted the tumor-suppressive activities of Notch and enable the oncogenic pathways activated by Notch to promote tumor growth. In this review, the authors detail the role of Notch pathway in head and neck cancers with a focus on HPV-associated cancers. In their contribution, Sandra and Jörg Reichrath summarize the impact of Notch signaling for carcinogenesis and progression of non-­ melanoma skin cancer (Reichrath and Reichrath 2020c). They explain that, since many decades, non-melanoma skin cancer (NMSC) is the most common malignancy worldwide. Basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) are the major types of NMSC, representing appr. 70% and 25% of these neoplasias, respectively. Because of their continuously rising incidence rates, NMSCs represent a constantly increasing global challenge for healthcare, although they are in most cases nonlethal and curable (e.g., by surgery). The authors elaborate that, while at present, carcinogenesis of NMSC is


still not fully understood, the relevance of genetic and molecular alterations in several pathways, including evolutionary highly conserved Notch signaling, has now been shown convincingly. Choosing NMSC as a model, the authors give in this review a brief overview on the interaction of Notch signaling with important oncogenic and tumor suppressor pathways and on its role for several hallmarks of carcinogenesis and cancer progression, including the regulation of cancer stem cells (CSCs), tumor angiogenesis, and senescence. In the next contribution, Rachael Guenter, Zeelu Patel, and Herbert Chen summarize the role of Notch signaling in thyroid cancer (Guenter et al. 2020). They explain that thyroid cancer is the most common malignancy of the endocrine system with a steadily rising incidence. The term thyroid cancer encompasses a spectrum of subtypes, namely, papillary thyroid cancer, follicular thyroid cancer, anaplastic thyroid cancer, and medullary thyroid cancer. Each subtype differs histopathologically and in degrees of cellular differentiation, which may be in part due to signaling of the Notch pathway. The Notch pathway’s role in cancer biology is controversial, as it has been shown to play both an oncogenic and tumor-­ suppressive role in many different types of cancer. This discordance holds true for each subtype of thyroid cancer, indicating that Notch signaling is likely cell type and context dependent. The authors explain that, whether oncogenic or not, Notch signaling has proven to be significantly involved in the tumorigenesis of thyroid cancer and has thus earned interest as a therapeutic target. The authors conclude that advancement in the understanding of Notch signaling in thyroid cancer holds great promise for the development of novel treatment strategies to benefit patients. In the following chapter, Zacharias Fasoulakis, George Daskalakis, Marianna Theodora, Panos Antsaklis, Michael Sindos, Michail Diakosavvas, Kyveli Angelou, Dimitrios Loutradis, and Emmanuel N Kontomanolis elaborate on the relevance of Notch signaling in cancer progression (Fasoulakis et  al. 2020). As they point out, the Notch signaling pathway controls cell prolifera-

J. Reichrath and S. Reichrath


tion, fate, differentiation, and cell death, by short-­ range signaling between nearby cells that come in contact. Fibroblasts, representing an essential for tumor growth component of stroma, have also been shown to be affected by Notch regulation. Notch gene mutations have been identified in a number of human tumors revealing information on the progression of specific cancer types, such as ovarian cancer and melanoma, immune-­ associated tumors such as myeloid neoplasms, but especially lymphocytic leukemia. The authors further explain that activation of Notch can be either oncogenic or it may contain growth-­ suppressive functions, acting as a tumor suppressor in other hematopoietic cells, hepatocytes, and skin and pancreatic epithelium. In the next contribution, Qiang Shen and Michael Reedijk elaborate on the role of Notch signaling for the breast cancer microenvironment (Shen and Reedijk 2020). They explain that Notch promotes breast cancer progression through tumor-initiating cell maintenance, tumor cell fate specification, proliferation, survival, and motility. In addition, Notch is recognized as a decisive mechanism in regulating various juxtacrine and paracrine communications in the tumor microenvironment (TME). In this chapter, we review recent studies on stress-mediated Notch activation within the TME and sequelae such as angiogenesis, extracellular matrix remodeling, changes in the innate and adaptive immunophenotype, and therapeutic perspectives. Last but not least, Giulia Monticone and Lucio Miele present a journey from notching phenotypes to cancer immunotherapy (Monticone and Miele 2020). The authors point out that Notch is a remarkable evolutionary conserved pathway, which has fascinated and engaged the work of investigators in an uncountable number of biological fields, from development of metazoans to immunotherapy for cancer. Nowadays Notch is the protagonist of some of the most cutting-edge fields including immunotherapy and synthetic biology. In their chapter, Monticone and Miele provide a comprehensive overview of the Notch field, with particular focus on the newest mechanistic and therapeutic advances and the future challenges of this constantly evolving field.

References Andersson ER, Sandberg R, Lendahl U (2011) Notch signaling: simplicity in design, versatility in function. Development 138:3593–3612. https://doi. org/10.1242/dev.063610 Das T, Zhong R, Spiotto MT (2020) Notch signaling and human papillomavirus-associated oral tumorigenesis. Adv Exp Med Biol 1287:105–122. Dexter JS (2014) The analysis of a case of continuous variation in Drosophila by a study of its linkage relations. Am Nat 48:712–758. Fasoulakis Z, Daskalakis G, Theodora M, Antsaklis P, Sindos M, Diakosavvas M, Angelou K, Loutradis D, Kontomanolis EN (2020) The relevance of notch signaling in cancer progression. Adv Exp Med Biol 1287:169–181 Gazave E, Lapébie P, Richards GS, Brunet F, Ereskovsky AV, Degnan BM, Borchiellini C, Vervoort M, Renard E (2009) Origin and evolution of the Notch signalling pathway: an overview from eukaryotic genomes. BMC Evol Biol 9:249. https://doi. org/10.1186/1471-2148-9-249 Giaimo BD, Gagliani EK, Kovall RA, Borggrefe T (2020) Transcription factor RBPJ as a molecular switch in regulating the Notch response. Adv Exp Med Biol 1287:9–30. Guenter R, Patel Z, Chen H (2020) Notch signaling in thyroid cancer. Adv Exp Med Biol 1287:155–168 Hunter GL, Giniger E (2020) Phosphorylation and proteolytic cleavage of Notch in canonical and non-canonical Notch signaling. Adv Exp Med Biol 1227(1):51–68 Jonusiene V, Sasnauskiene A (2020) Notch and endometrial cancer. Adv Exp Med Biol 1287:47–58 Kawaguchi K, Kaneko S (2020) Notch signaling and liver cancer. Adv Exp Med Biol 1287:69–80 Kidd S, Kelley MR, Young MW (1986) Sequence of the notch locus of Drosophila melanogaster: relationship of the encoded protein to mammalian clotting and growth factors. Mol Cell Biol 6(9):3094–3108 Li Y, Li Y, Chen X (2020) NOTCH and esophageal squamous cell carcinoma. Adv Exp Med Biol 1287:59–68 Monticone G, Miele L (2020) Notch pathway: a journey from notching phenotypes to cancer immunotherapy. Adv Exp Med Biol 1287:201–222 Morgan TH (1917) The theory of the gene. Am Nat 19:309–310. New Haven, USA. https://doi. org/10.1086/279629 Morgan T (1928) The theory of the gene (revised ed. 1928), vol 4. Yale University Press, New Haven, USA pp 77–81 Porcheri C, Mitsiadis TA (2020) Notch in head and neck cancer. Adv Exp Med Biol 1287:81–103 Reichrath J, Reichrath S (2020a) A snapshot on the molecular biology of Notch signaling: challenges and promises. Adv Exp Med Biol 1227:1–7 Reichrath J, Reichrath S (2020b) Notch signaling and tissue patterning in embryology: an introduction. Adv Exp Med Biol 1218:1–7

1  Notch Signaling in Prevention And Therapy: Fighting Cancer with a Two-Sided Sword


Symp Quant Biol 74:81–90. Reichrath J, Reichrath S (2020c) The impact of Notch sqb.2009.74.028 signaling for carcinogenesis and progression of non-­ melanoma skin cancer: lessons learned from cancer Shen Q, Reedijk M (2020) Notch signaling and the breast cancer microenvironment. Adv Exp Med Biol stem cells, tumor angiogenesis, and beyond. Adv Exp 1287:183–200. Med Biol 1287:123–154. Reiff T, Baeumers M, Tibbe C, Klein T (2020) Unraveling Wharton KA, Johansen KM, Xu T, Artavanis-Tsakonas S (1985) Nucleotide sequence from the neurogenic of hidden secrets: the tumour suppressor lethal (2) locus notch implies a gene product that shares homolgiant discs (Lgd)/CC2D1, Notch signaling and cancer. ogy with proteins containing EGF-like repeats. Cell Adv Exp Med Biol 1287:31–46. 43(3 Pt 2):567–581 Richards GS, Degnan BM (2009) The dawn of developmental signaling in the metazoa. Cold Spring Harb


Transcription Factor RBPJ as a Molecular Switch in Regulating the Notch Response Benedetto Daniele Giaimo, Ellen K. Gagliani, Rhett A. Kovall, and Tilman Borggrefe


The Notch signal transduction cascade requires cell-to-cell contact and results in the proteolytic processing of the Notch receptor and subsequent assembly of a transcriptional coactivator complex containing the Notch intracellular domain (NICD) and transcription factor RBPJ. In the absence of a Notch signal, RBPJ remains at Notch target genes and dampens transcriptional output. Like in other signaling pathways, RBPJ is able to switch from activation to repression by associating with corepressor complexes containing several chromatin-modifying enzymes. Here, we focus on the recent advances concerning RBPJ-corepressor functions, especially in regard to chromatin regulation. We put this into the context of one of the best-studied model systems for Notch, blood cell development. Alterations in the RBPJ-corepressor functions can contribute to the development of

B. D. Giaimo (*) · T. Borggrefe (*) Institute of Biochemistry, University of Giessen, Giessen, Germany e-mail: [email protected]; [email protected] E. K. Gagliani · R. A. Kovall Department of Molecular Genetics, Biochemistry and Microbiology, University of Cincinnati College of Medicine, Cincinnati, OH, USA

leukemia, especially in the case of acute myeloid leukemia (AML). The versatile role of transcription factor RBPJ in regulating pivotal target genes like c-MYC and HES1 may contribute to the better understanding of the development of leukemia. Keywords

Notch · SHARP · KyoT2/FHL1C · L3MBTL3 · H2A.Z · p400 · Tip60 · AML1/ ETO · Leukemia

Abbreviations ADAM A disintegrin and metalloproteinase AE AML1/ETO AE9a AML1/ETO 9a AEtr AML1/ETO truncated AF9 ALL1-fused gene from chromosome 9 protein AMKL Acute megakaryoblastic leukemia AML Acute myeloid leukemia AML1 Acute myeloid leukemia 1 ANKs Ankyrin repeats B-ALL B-cell acute lymphoblastic leukemia CARM1 Coactivator-associated arginine methyltransferase 1

© Springer Nature Switzerland AG 2021 J. Reichrath, S. Reichrath (eds.), Notch Signaling in Embryology and Cancer, Advances in Experimental Medicine and Biology 1287,


B. D. Giaimo et al.


CBF1 C promoter-binding factor 1 CBFβ Core-binding factor β CDK8 Cyclin-dependent kinase 8 CKII Casein kinase II CLL Chronic lymphocytic leukemia CoA Coactivator CoR Corepressor CSL Homo sapiens CBF1, Drosophila melanogaster Suppressor of Hairless, and Caenorhabditis elegans Lag-1 CtBP C-terminal-binding protein CtIP CtBP-interacting protein DDX5 DEAD-box helicase 5 DLBCL Diffuse large B-cell lymphoma DLL1 DELTA-LIKE 1 DLL4 DELTA-LIKE 4 dnMAML1 dominant-negative MAML1 EBNA2 Epstein-Barr virus nuclear antigen 2 EGR2 Early growth response 2 Ep300 E1A-binding protein P300 Ep400 E1A-binding protein P400 ESCs Embryonic stem cells ETO Eight-twenty-one FBXW7 F-Box and WD repeat domain-­ containing 7 FHL1C Four-and-a-half LIM domain protein 1C FLT3 FMS-like tyrosine kinase 3 GCN5 General control of amino acid synthesis protein 5-like 2 GoF Gain of function GSI γ-secretase inhibitor H2A.Zac H2A.Z acetylation HAT Histone acetyltransferase HD heterodimerization domain HDACs Histone deacetylases Hes1 Hairy and Enhancer of Split 1 HPCs Hematopoietic progenitor cells KAT lysine acetyltransferase KAT2A lysine acetyltransferase 2A KAT2B lysine acetyltransferase 2B KAT3B lysine acetyltransferase 3B KAT5 lysine acetyltransferase 5 KBF2 H-2 K binding factor-2 KDM1A lysine demethylase 1A KDM5A lysine demethylase 5A


lysine demethylase 7B lysine-specific methyltransferase 2A KMT2D lysine-specific methyltransferase 2D L3MBTL3 lethal (3) malignant brain tumor-­ like protein 3 LID Little imaginal discs LoF Loss of function LSD1 lysine-specific demethylase 1 Lz Lozenge MAL Megakaryocytic acute leukemia MAM Mastermind MAML Mastermind-like MCL Mantle cell lymphomas MINT MSX2-interacting protein MKL1 Megakaryoblastic leukemia 1 MLL Mixed-lineage leukemia MS Mass spectrometry MTG16 Myeloid translocation gene on chromosome 16 protein MTG8 Myeloid translocation gene on 8q22 MTGR1 Myeloid translocation gene-­ related protein 1 NACK Notch activation complex kinase NCoR Nuclear receptor corepressor NFAT Nuclear factor of activated T-cells NF-κB1 Nuclear factor kappa B subunit 1 NHR Nervy homology regions NICD NOTCH intracellular domain NICD1 NOTCH1 intracellular domain 1 NK Natural killer OTT One twenty-two PCAF Ep300-CBP-associated factors PEST Proline, glutamic acid, serine, and threonine PHF8 PHD finger protein 8 PRMT4 Protein arginine methyltransferase 4 PTMs Posttranslational modifications RBM15 RNA-binding motif protein 15 RBPID RBPJ-interacting domain RBPJ Recombination signal-binding protein for immunoglobulin kappa J region RBS RBPJ-binding sites RHD Runt homology domain

2  Transcription Factor RBPJ as a Molecular Switch in Regulating the Notch Response


Runt-related transcription factor Runt-related transcription factor 1 SMRT and HDACs-associated repressor protein SMRT Silencing mediator for retinoid and thyroid receptor SMZL Splenic marginal zone lymphomas Spen split ends SPOC Spen paralog and ortholog C-terminal SPOCome SPOC interactome SRA Steroid receptor coactivator SuH Suppressor of Hairless TAD Transactivation domain T-ALL T-cell acute lymphoblastic leukemia TFs transcription factors Tip60 HIV-1 Tat-interactive protein, 60 kDa UTR Untranslated region WT Wild type ZnF Zinc fingers

Introduction Notch signaling is an evolutionary highly conserved pathway that plays a pivotal role in many cellular and developmental processes including T-cell development (Vijayaraghavan and Osborne 2018) and angiogenesis (Pitulescu et  al. 2017; Tetzlaff and Fischer 2018). Although Notch was originally described as a neurogenic gene in Drosophila melanogaster, the first analysis of Drosophila embryos made it clear that Notch signals are pleiotropic, affecting many tissues. After the cloning and sequencing of the Notch gene in the 1980s, it became clear that Notch is a ­single-­pass transmembrane receptor. Subsequently, the NOTCH1 gene was described to be a hotspot for chromosomal translocations in human T-cell acute lymphoblastic leukemia (T-ALL) (Ellisen et al. 1991). By now, we know that NOTCH1 mutations are found not only in human T-ALL (Weng et  al. 2004) but also in other forms of human leukemia, for example,


chronic lymphocytic leukemia (CLL) (Puente et  al. 2011) as well as many other cancer types (Giaimo and Borggrefe 2018). At the molecular level, Notch signal transduction bears some unique features not seen in other pathways like TGFβ, Wnt, or Hedgehog signaling [also reviewed in Borggrefe et al. 2016]. For example, the Notch pathway does not involve any second messengers. Notch signaling occurs through direct interactions between the Notch receptor and its ligand exposed on neighboring cells (Fig. 2.1). Upon ligand binding, the extracellular protease cleavage site of the receptor is exposed and cleaved by ADAM (a disintegrin and metalloproteinase) proteases. Subsequently, a second cleavage of the receptor is mediated by a γ-secretase-containing complex leading to the release of the Notch intracellular domain (NICD), which is itself a transcriptional coactivator (Fig.  2.1). The NICD migrates into the nucleus and functions as a transcriptional coactivator together with RBPJ and mastermind (MAM) [reviewed in Oswald and Kovall 2018]. The transcription factor RBPJ is a central molecular switch in the Notch pathway and mediates either transcriptional repression or activation of Notch target genes (Fig. 2.1).

 ranscription Factor RBPJ T in Balancing Notch Target Gene Expression Historically, RBPJ was discovered thirty years ago and was originally named RBPJκ [recombination signal binding protein for immunoglobulin kappa J region, (Hamaguchi et al. 1989)]. It also has different names, such as CBF1 (C promoter binding factor 1) or KBF2 [H-2K binding factor-2, (Brou et  al. 1994)] and belongs to the CSL (Homo sapiens CBF1, Drosophila melanogaster Suppressor of Hairless and Caenorhabditis elegans Lag-1) protein family. The DNA binding sequence was identified as 5′-CGTGGGAA-3′ (Tun et al. 1994) and recent studies investigated the genome-wide distribution of RBPJ in several different tissues (Dieguez-Hurtado et  al. 2019; Petrovic et al. 2019; Wang et al. 2011; Xie et al.


B. D. Giaimo et al.

Fig. 2.1  The Notch signaling cascade. In absence of Notch signaling, the DNA-binding protein RBPJ is bound at the RBPJ-binding sites (RBS) where it recruits corepressors (CoR) preventing the expression of Notch target genes. The binding of ligands to Notch receptors induces a conformational change that allows their proteolytic cleavage by ADAM proteases producing an intermediate product known as NotchΔE. Subsequently, a γ-secretase-­ containing complex catalyzes a second cleavage of the Notch receptor releasing the Notch intracellular domain

(NICD). The free NICD moves into the nucleus where it interacts with RBPJ and forms a trimeric complex together with Mastermind-like (MAML). This trimeric complex recruits additional coactivators (CoA) finally promoting expression of Notch target genes. Finally, proteasome-­ dependent degradation of the NICD terminates the signal, and the RBPJ-associated corepressor complex is reassembled at the RBS inducing repression of Notch target genes. Green and red balls indicate positive and negative histone marks, respectively

2016; Zhao et al. 2011). RBPJ shares some structural similarities with Rel Homology Domain proteins such as NF-κB1 (nuclear factor kappa B subunit 1) and NFAT [nuclear factor of activated T-cells, (Kovall and Hendrickson 2004)]. It is the centerpiece of transcriptional regulation in Notch signaling, acting as a molecular hub for interactions of either corepressor or coactivators. In the absence of a Notch signal, RBPJ interacts with the cofactor SHARP recruiting histone deacetylase-­ containing corepressor complexes. In the presence of a Notch signal, a ternary complex containing RBPJ, NICD and MAM-like (MAML) is assembled and expression of Notch target genes is induced (Fig.  2.1). The RBPJ/

NICD/MAML-containing coactivator complex also recruits lysine acetyltransferases (KATs) such as KAT3B/Ep300 (lysine acetyltransferase 3B/E1A binding protein P300), KAT2B/PCAF (lysine acetyltransferase 2B/Ep300-CBP-­ associated factors) and KAT2A/GCN5 [lysine acetyltransferase 2A/ general control of amino acid synthesis protein 5-like 2, (Kurooka and Honjo 2000; Oswald et al. 2001)]. Interestingly, RBPJ was initially described as a repressor of transcription and its role as a molecular switch was further underscored by the finding that repression and activation via RBPJ involves the recruitment of distinct protein complexes [reviewed in (Borggrefe and Oswald 2009]. From

2  Transcription Factor RBPJ as a Molecular Switch in Regulating the Notch Response


Table 2.1  List of well-defined interactors of the main components of the Notch signaling pathway: L3MBTL3, NICD, RBPJ, and SHARP Interactor L3MBTL3 interactors KDM1A/LSD1



Xu et al. 2017


NICD interactors CARM1/PRMT4

Hein et al. 2015


Cyclin C/CDK8

Fryer et al. 2004


DDX5 Ep400/Tip60 complex

Jung et al. 2013; Lin et al. 2013 Giaimo et al. 2018

n.d. n.d.


Kurooka and Honjo 2000 Kurooka and Honjo 2000

n.d. n.d.


Oswald et al. 2001



Wu et al. 2000

Nam et al. 2006; Wilson and Kovall 2006


Jin et al. 2017; Weaver et al. 2014


SRA RBPJ interactors EBNA2

Jung et al. 2013


Grossman et al. 1994; Henkel et al. 1994; Ling et al. 1993; Waltzer et al. 1994; Zimber-Strobl et al. 1994


Ep400/Tip60 complex

Giaimo et al. 2018



Geimer Le Lay et al. 2014



Liefke et al. 2010



Yatim et al. 2012



Taniguchi et al. 1998 Liang et al. 2008

Collins et al. 2014 n.d.


Xu et al. 2017 Fortini and Artavanis-­Tsakonas 1994

n.d. Nam et al. 2006; Wilson and Kovall 2006


Ma et al. 2007



Oswald et al. 2002 Wacker et al. 2011

Yuan et al. 2019 Tabaja et al. 2017

RTA SHARP interactors AML1/ETO

Liang et al. 2002


Salat et al. 2008; Thiel et al. 2017



Oswald et al. 2005 Oswald et al. 2016 Salat et al. 2008 Engel et al. 2010 Engel et al. 2010 Oswald et al. 2016

n.d. n.d. n.d. n.d. n.d. n.d.

these studies a model emerged (Fig. 2.1) stating that presence of NICD converts the RBPJ-­ corepressor to the RBPJ-NICD-coactivator complex (Borggrefe and Oswald 2009; Bray 2006). In the recent years, the RBPJ interactome has been extensively studied [(Borggrefe and Liefke

2012; Guruharsha et  al. 2014; Ho et  al. 2018; Yatim et  al. 2012) and Table  2.1] in order to understand at the molecular level how gene repression and activation are regulated. As part of the corepressor complex, RBPJ can directly interact with corepressor SHARP [SMRT (silencing


B. D. Giaimo et al.

Fig. 2.2  Overview on the known crystal structures of RBPJ-associated complexes. (a) The structure of the Caenorhabditis elegans RBPJ/NICD/MAML ternary activation complex (PDBID: 2FO1). RBPJ, shown in cyan with a transparent white surface, consists of three major domains. The N-terminal domain (NTD) makes direct contacts primarily with MAML (red) and DNA (blue). The beta-trefoil domain (BTD) interacts with DNA and NICD (yellow). The C-terminal domain (CTD) interacts with MAML and NICD. (b) The structure of the Mus musculus RBPJ/SHARP repressor complex (PDBID: 6DKS). Like NICD, SHARP (orange) also binds the CTD and

BTD of RBPJ. (c) Top: Structural representation of multiple corepressors that bind the BTD of RBPJ similarly. NICD (yellow) PDBID, 3 V79; SHARP (orange) PDBID, 6DKS; KyoT2/FHL1C (pink) PDBID, 4J2X; and RITA (light green) PDBID, 5EG6. Bottom: Multiple sequence alignments of coregulators that bind the BTD of RBPJ. Boxed in red is the highly conserved hydrophobic tetrapeptide seen in all four mammalian Notch isoforms as well as some corepressors. The blue boxes represent other highly conserved hydrophobic residues seen in multiple corepressors

mediator for retinoid and thyroid receptor) and HDACs (histone deacetylases)-associated repressor protein], also known as mouse MINT (MSX2interacting protein) or Spen [split ends (Oswald et al. 2002)]. Recently, we determined the binding surfaces of the RBPJ/SHARP i­nteraction at atomic resolution using X-ray crystallography [Fig. 2.2 (Yuan et al. 2019)]. Based on the RBPJ/ SHARP structure, we could design a dominantnegative form of SHARP in a Notch-­OFF state (Giaimo et al. 2017a; Xu et al. 2017; Yuan et al. 2019). When overexpressing the wild-­type (WT) form of the RBPJ-interacting domain (RBPID) of SHARP, derepression of Notch target genes was observed; however, this was not the case when, based on the crystal structure, we mutated two amino acids within this domain (Yuan et al. 2019). Previous studies linked the repressive activity of SHARP to HDACs (Oswald et al. 2002; Oswald et  al. 2016), and, in line with these studies, we observed increased histone acetylation upon overexpression of the WT but not the mutant RBPID

(Yuan et  al. 2019). Importantly, RBPJ depletion leads to derepression of Notch target genes in the same setting. This phenotype is efficiently rescued by a WT RBPJ but not a mutant in which the residues required for its interaction with SHARP are mutated (Yuan et al. 2019). SHARP is a protein of more than 400  kDa characterized by a highly conserved SPOC (Spen paralog and ortholog C-terminal) domain which has a strong transcriptional repressive activity that depends on CtIP/CtBP (CtBP-interacting protein/C-terminal-binding protein) (Oswald et al. 2005). To better dissect the mechanism of the RBPJ/SHARP-mediated transcriptional repression, we have recently characterized, by mass spectrometry (MS), the SPOC interactome (SPOCome) (Oswald et al. 2016). This approach identified the HDACs-containing NCoR (nuclear receptor corepressor) complex, explaining how HDACs are recruited to RBPJ-bound enhancer sites; however, it also identified the KMT2D (lysine-specific methyltransferase 2D) complex

2  Transcription Factor RBPJ as a Molecular Switch in Regulating the Notch Response


Fig. 2.3  Intermediate states involved in the transcriptional regulation of Notch target genes. The different RBPJ-associated corepressor complexes (SHARP, L3MBLT3, and KyoT2) are recruited at the same RBPJ-­ binding sites (RBS) in a well-defined temporal order and/ or tissue-specific manner to promote repression of Notch target genes. Of note, SHARP can interact with the

HDAC-containing NCoR corepressor complex when it is phosphorylated on two serine residues. NCoR recruitment moves the balance toward repression alternatively; NCoR interacts with the KMT2D-containing complex moving the balance toward gene activation. L3MBTL3 bridges the histone demethylase KDM1A/LSD1 (indicated as KDM1A) to RBPJ at RBS

(Oswald et  al. 2016). This finding was quite unexpected as the KMT2D complex is involved in transcriptional activation in contrast to the repressive activity of the SPOC domain of SHARP. Previous structural studies of SMRT, the ortholog of NCoR, in complex with the SPOC domain of SHARP unveiled that this interaction depends on the phosphorylation of highly conserved serine residues of SMRT by casein kinase II (CKII) (Mikami et  al. 2013; Mikami et  al. 2014). Of note, NCoR is also phosphorylated on serine residues at its C-terminus (Yoo et al. 2012, 2013), and we found that NCoR phosphorylation is required for its interaction with the SPOC domain and dependent on CKII [(Oswald et  al. 2016) and Fig.  2.3]. KMT2D and NCoR are in competition for binding to SPOC, and phospho-­ NCoR displaces KMT2D leading to transcriptional repression [(Oswald et  al. 2016) and Fig. 2.3]. These data support the hypothesis that

SHARP, integrating different stimuli, acts as a poising factor for Notch target genes, balancing repressive and activating histone marks [(Giaimo et al. 2017b; Oswald et al. 2016) and Fig. 2.3]. The SPOC domain of SHARP directly interacts with ETO [eight-twenty-one, also known as MTG8 (myeloid translocation gene on 8q22)] which acts as a corepressor of Notch target genes by meaning of deacetylation (Salat et al. 2008). ETO is a member of the MTG family of corepressors of transcription which includes also MTGR1 (myeloid translocation gene-related protein 1) and MTG16 (myeloid translocation gene on chromosome 16 protein). Both MTGR1 and MTG16 interact with RBPJ; however, only MTG16 is displaced from RBPJ by the NOTCH1 intracellular domain 1 (NICD1) (Engel et  al. 2010). In conclusion, the SPOC domain of SHARP is able to interact with several different proteins. It remains to be investigated how the


varying interaction partners are recruited to enhancers. Our favorite working hypothesis is that posttranslational modifications (PTMs) such as phosphorylation determine specificity in terms of composition and strengths of recruitment of corepressors. In that regard, it is appealing that the highly conserved SPOC domain interacts with double-phosphorylated peptide (Oswald et al. 2016). This might be also the case for other SPOC-interaction partners. Interestingly, RBM15 [RNA-binding motif protein 15, also known as OTT (one twenty-two)], another SPOC domain-­ containing protein, was shown to modulate the Notch signaling pathway in a cell-type-specific fashion (Ma et al. 2007), marking the importance of the SPOC domain-containing proteins in the regulation of the Notch signaling pathway. Another direct interactor of RBPJ is KyoT2 [also known as FHL1C (four-and-a-half LIM domain protein 1C) in human] which, competing with the NICD1, represses transcription of target genes (Collins et al. 2014; Taniguchi et al. 1998). The structure of RBPJ in complex with KyoT2/ FHL1C reveals a good overlap with the RBPJ/SHARP and RBPJ/Notch binding surfaces [Fig. 2.2 (Collins et al. 2014; Yuan et al. 2019)]. One more isoform, KyoT3/FHL1B, is also able to interact with RBPJ and to promote gene repression (Liang et al. 2008), but this is not the case for the isoform KyoT1/FHL1A (Taniguchi et al. 1998). It remains to elucidate whether the repressive mechanism of KyoT2/FHL1C and KyoT3/ FHL1B is exclusively based on their competition with the NICD or whether it depends on other cofactors, for example, a link between KyoT2/ FHL1C and Polycomb has been proposed (Quin et  al., PMID, 14999091, and Quin et  al., 15,710,417). As part of the corepressor complex, RBPJ recruits histone demethylase activities such as KDM5A/LID [lysine demethylase 5A/little imaginal discs (Di Stefano et al. 2011; Liefke et al. 2010; Moshkin et al. 2009)] and KDM1A/LSD1 [lysine demethylase 1A/lysine-specific demethylase 1 (Di Stefano et  al. 2011; Mulligan et  al. 2011; Xu et  al. 2017; Yatim et  al. 2012)]. KDM5A/LID directly interacts with RBPJ and demethylates H3K4me3 at RBPJ-bound enhancer

B. D. Giaimo et al.

sites promoting repression of Notch target genes (Liefke et al. 2010), while KDM1A/LSD1 indirectly interacts with RBPJ via L3MBTL3 [lethal (3) malignant brain tumor-like protein 3] (Xu et al. 2017). We identified L3MBTL3 in a screen for RBPJ interactors and observed that the L3MBTL3-RBPJ interaction is conserved in Drosophila melanogaster and Caenorhabditis elegans (Xu et al. 2017). Notably, L3MBTL3 and NICD1 bind to the same binding surface on RBPJ: While NICD1 displaces L3MBTL3 from RBPJ, the latter does not outcompete NICD1 for binding to RBPJ (Xu et  al. 2017). The recruitment of KDM1A/LSD1 via L3MBTL3 is required to modulate H3K4 methylation states at RBPJ-bound enhancers promoting repression of target genes (Xu et  al. 2017). In line with that, pharmacological inhibition of KDM1A/LSD1 leads to upregulation of Notch target genes (Augert et al. 2019); however it must be marked that, at least in lung cancer cells, KDM1A/LSD1 may indirectly regulate the Notch signaling pathway via a direct regulation of the expression of NOTCH1 (Augert et al. 2019). A previous study linked KDM1A/LSD1 to repression of Notch target genes, but the authors also observed that KDM1A/LSD1 associates with the NOTCH1 coactivator complex to modulate H3K9 methylation states and finally promoting expression of Notch target genes (Yatim et al. 2012). Altogether, these data suggest that KDM1A/LSD1 acts as both an activator and a repressor of the Notch-­ dependent gene expression program. Finally, the demethylase KDM7B/PHF8 (lysine demethylase 7B/PHD finger protein 8) is also part of the NOTCH1 coactivator complex and supports expression of Notch targets by modulating H3K27 methylation states (Yatim et al. 2012). Based on the available structural and biophysical data, SHARP, KyoT2/FHL1C, and L3MBTL3 interact in a mutually exclusive fashion with RBPJ: Different intermediate complexes may be dynamically recruited at the same enhancer in a defined temporal order or in a tissue-­specific manner to modulate the chromatin structure leading to gene repression (Fig.  2.3). Since the RBPJ-associated cofactors interactions are strong and the DNA-binding affinity of RBPJ

2  Transcription Factor RBPJ as a Molecular Switch in Regulating the Notch Response

is relatively weak, it can be assumed that the different RBPJ complexes are constantly exchanging, explaining how the different cofactors are recruited at a defined enhancer. The activation of the Notch pathway leads to the release of the NICD from the cell membrane which, upon nuclear translocation, converts RBPJ from a repressor to an activator of transcription via the recruitment of additional coactivators (Fig.  2.1). One of the most important members of the coactivator complex is MAM which, together with RBPJ and NICD, forms a trimeric complex indispensable for activation of Notch target genes (Friedmann et  al. 2008; Fryer et  al. 2002; Kitagawa et  al. 2001; Nam et al. 2006; Wilson and Kovall 2006; Wu et al. 2000, 2002). The human Mastermind family (Mastermind-like or MAML) consists of three members, all of them able to support Notch-­ dependent transcription (Lin et  al. 2002). Probably, the most important function of MAML is to recruit the histone acetyltransferase (HAT) KAT3B/Ep300 to Notch target genes that supports gene expression via histone acetylation (Fryer et  al. 2002; Jung et  al. 2013; Oswald et al. 2001; Tottone et al. 2019; Wallberg et al. 2002). Additionally, KAT3B/Ep300 acetylates MAML leading to the recruitment of the coactivator NACK (Notch activation complex kinase) at Notch target genes (Jin et  al. 2017; Weaver et  al. 2014). MAML also recruits the cyclin C/CDK8 (Cyclin-dependent kinase 8) complex that phosphorylates the NICD leading to its proteasome-­dependent degradation (Fryer et  al. 2004). Another component of the Notch coactivator complex is the RNA helicase DDX5 (DEAD-box helicase 5) which, interacting with the long noncoding RNA SRA (steroid receptor coactivator), supports the recruitment of KAT3B/Ep300 and subsequent activation of Notch target genes (Jung et al. 2013; Lin et al. 2013). Furthermore, CARM1/PRMT4 (coactivator-associated arginine methyltransferase 1/ protein arginine methyltransferase 4) promotes the activation of Notch target genes by arginine methylation of the NICD1 itself (Hein et  al. 2015).


Recently, we characterized the interactome of the cleaved, active NICD1  in mouse progenitor cells (Giaimo et al. 2018). Using this approach, we identified the Ep400-KAT5/Tip60 (E1A-­ binding protein P400-lysine acetyltransferase 5/ HIV-1 Tat-interactive protein, 60  kDa) complex (hereafter referred to as Ep400/Tip60 complex) as an NICD1 interactor. This complex attracted our attention as its subunits Ep400 and KAT5/ Tip60 have been previously linked to deposition (Gevry et al. 2007) and acetylation (Kusch et al. 2004) of the histone variant H2A.Z, respectively. H2A.Z has been linked to several processes including heterochromatin regulation, DNA repair, and gene transcription both in a positive and negative fashion (Giaimo et  al. 2019). We found that H2A.Z depletion leads to upregulation of Notch target genes, and this enhanced expression is associated with increased active marks, namely, H3K4me2 and H3K27ac, at Notch-­ dependent enhancer elements. These data suggest H2A.Z as a negative regulator of Notch target genes, and this conclusion is further supported by the observation that activation of Notch signaling leads to decreased H2A.Z occupancy at Notch-dependent enhancers (Giaimo et al. 2018). However, while H2A.Z occupancy negatively correlates with induction of Notch target genes, acetylation of H2A.Z (H2A.Zac) does it in a positive manner suggesting that H2A.Z is involved in both gene repression and activation and the difference between the two functions is obtained via its acetylation. Overexpression of H2A.Z leads to upregulation of Notch target gene Hairy and Enhancer of Split 1 (Hes1), while this upregulation is more modest when an acetylation-­ defective H2A.Z mutant is overexpressed (Giaimo et  al. 2018). Our data further indicate that acetylation of H2A.Z is highly dynamic, which also reconciles previous contrasting results showing H2A.Z as a repressor or an activator of transcription (Gevry et  al. 2007, 2009; Giaimo et  al. 2019). We observed that Ep400 interacts with RBPJ and it is recruited to Notch-dependent enhancers in a Notch-dependent fashion (Giaimo et al. 2018). Furthermore, making use of a tethering approach, we could show that Tip60 promotes H2A.Zac supporting gene expression


B. D. Giaimo et al.

Fig. 2.4  Model for the regulation of Notch target gene by the Ep400/Tip60 complex and histone variant H2A.Z.  In the repressed (OFF) or poised state, RBPJ directly interacts with Ep400 leading to the recruitment of the Ep400/Tip60 complex. This interaction is unstable but sufficient to promote deposition of the histone variant

H2A.Z. Upon activation of the Notch pathway (ON), the Notch intracellular domain (NICD) directly interacts with RBPJ and Ep400 leading to stabilization of the RBPJ-Ep400 interaction. In turn, this results in acetylation of H2A.Z (indicated with green balls) and finally gene activation

(Giaimo et al. 2018). In summary, our data suggest that in a Notch-OFF or poised state, the Ep400/Tip60 complex is recruited to Notch-­ dependent enhancer sites via an unstable interaction with RBPJ promoting loading of H2A.Z.  Upon Notch activation, the interaction between the Ep400/Tip60 complex and RBPJ is stabilized via additional interactions with the NICD1 protein promoting acetylation of H2A.Z and finally gene expression (Fig. 2.4). The classical model for the regulation of Notch target genes suggests that RBPJ is persistently bound to its cognate sequences promoting gene repression or activation based on the stimulation of the NOTCH receptor. However, recent studies challenged this model and suggest that RBPJ is weakly bound to its enhancers in absence of stimulus, while its genomic occupancy significantly increases upon activation of the Notch pathway and landing of the NICD at target enhancers (Fig. 2.5). Earlier studies in Drosophila melanogaster cell lines observed increased occupancy of Su(H) (Suppressor of Hairless), the Drosophila homolog of RBPJ, upon induction of Notch signaling (Krejci and Bray 2007). Recently, single-molecule tracking in vivo studies allowed to define that Su(H) transiently binds

the DNA in the OFF state (Gomez-Lamarca et al. 2018). Upon Notch activation, the DNA binding of Su(H) significantly increases (Gomez-­ Lamarca et al. 2018). Similarly to Drosophila, activation of the Notch pathway leads to increased RBPJ occupancy in mammalian cell lines (Castel et al. 2013; Wang et  al. 2014; Yashiro-Ohtani et  al. 2014); however, Castel and colleagues identified two different classes of RBPJ-binding sites: dynamic sites at which RBPJ is bound only upon Notch activation and static sites at which RBPJ is bound independently of the Notch activation (Castel et al. 2013). To note, NICD binding occurs exclusively at the dynamic but not static sites, and furthermore, Castel and colleagues observed that RBPJ depletion leads to derepression of few genes associated with static sites and about 50% of the genes associated with dynamic sites (Castel et al. 2013). However, this analysis uses different cell lines for ChIP-Seq (C2C12 cell lines) and gene expression analysis (quiescent satellite cells) (Castel et al. 2013). As a consequence, we do not know whether all the derepressed genes assumed to be associated with static or dynamic RBPJ sites are so. The DNA-binding strength of RBPJ does not seem to be regulated exclusively

2  Transcription Factor RBPJ as a Molecular Switch in Regulating the Notch Response


Fig. 2.5  New model for regulation of Notch target genes. (a) The classic model for regulation of Notch target genes is based on the binding of RBPJ at its cognate RBPJ-­ binding sites (RBS) in absence of Notch signaling. In this scenario, RBPJ recruits corepressors (CoR) preventing expression of target genes. (b) New data suggest that

RBPJ transiently binds to the RBS in absence of Notch signaling promoting gene repression. Upon Notch activation, the cleaved Notch intracellular domain (NICD) interacts with RBPJ leading to increased DNA binding of RBPJ at the RBS. This event leads finally to activation of Notch target genes

by the NICD, for example, a recent study proposed that HDAC1 and KDM5A/LID play a negative and positive role, respectively, in this process, at least in mitosis (Dreval et  al. 2019). Similarly, the BRM complex promotes Su(H) binding in Drosophila (Pillidge and Bray 2019). The above findings implicate dynamic binding of RBPJ depending on dynamic coactivator binding. Promoter specificity might also be achieved by the usage of mono- versus dimeric RBPJ-­ bound enhancers. In fact, several RBPJ enhancers are characterized by two correctly spaced and oriented binding motifs at which a dimeric NICD1/RBPJ/MAML complex is recruited (Hass et  al. 2015; Nam et  al. 2007; Severson et  al. 2017). The structure of the dimeric NICD1/ RBPJ/MAML complex has been solved (Arnett et al. 2010); however, we do not know the impact of PTMs of the NICD on the dimeric NICD1/ RBPJ/MAML complex formation (Borggrefe et al. 2016). The DNA binding of RBPJ is also dependent on other transcription factors (TFs). This is, for example, marked by the loss of function (LoF) of Lozenge (Lz), the Drosophila homolog of Runx

(Runt-related transcription) factors, which results in reduced SuH occupancy (Terriente-Felix et al. 2013). Similarly, Lz overexpression leads to increased SuH occupancy and increased response to Notch activation (Skalska et al. 2015). In line with that, the Runx DNA-binding motif is found near the RBPJ-binding sites (Wang et al. 2011), and RBPJ and RUNX1 [(Runt-related transcription factor 1) also known as AML1 (acute myeloid leukemia 1)] colocalize genome-wide (Wang et  al. 2014). In Drosophila, the basic helix-loop-helix (bHLH) TFs Twist and Dorsal prime RBPJ-dependent enhancers leading to synchronized and sustained enhancer activity (Falo-­ Sanjuan et al. 2019), marking the importance of tissue-specific TFs in the Notch response. Additionally, RBPJ colocalizes and interacts with the DNA-binding protein IKAROS which is required for repression of Notch target genes (Geimer Le Lay et al. 2014). However, the exact relationship between RBPJ and IKAROS is not clear, and we do not know whether their interaction is required to support the DNA binding of RBPJ and vice versa. This can be addressed by performing depletion of IKAROS followed by ChIP versus RBPJ and the other way round.


Notch Signaling in Hematopoiesis The essential role for Notch signaling in inducing T-cell development has been extensively investigated [reviewed in Vijayaraghavan and Osborne 2018]. Inducible depletion of the Notch1 gene in bone marrow precursors results in a block of T-cell development associated with ectopic appearance of donor progenitor-derived B220+ immature B-cells in the thymus (Radtke et  al. 1999; Wilson et  al. 2001). Accordingly, RBPJ conditional knockout mice are characterized by a block in T-cell development associated with appearance of B-cells in the thymus (Han et al. 2002). Similar results were obtained by gain of function (GoF) of the Notch target gene Deltex1 (Izon et  al. 2002) or by overexpression of a dominant-­ negative MAML1 (dnMAML1) (Maillard et al. 2004). These data suggest Notch signaling as the driver of the T-cell differentiation program, and in line with that, retroviral expression of the NICD in murine hematopoietic precursors, followed by transplantation into recipient mice, leads to an abnormal appearance of immature double-positive T-cells in the bone marrow and subsequent development of T-cell leukemia, while B-cell development is blocked (Pear et al. 1996; Pui et  al. 1999). Furthermore, MTG16 knockout results in defects in T-cell differentiation both in mice and using MTG16−/− hematopoietic progenitors (Engel et al. 2010; Hunt et al. 2011). The critical role of Notch signaling in activating the T-cell lineage differentiation program is also marked by the observation that the engagement of NOTCH receptors by DELTA-LIKE 1 (DLL1) ligand expressed on the surface of OP9 stromal cells leads to the differentiation of hematopoietic progenitor cells (HPCs) and embryonic stem cells (ESCs) into T-cells (Schmitt et  al. 2004b; Schmitt and Zuniga-Pflucker 2002). The thymus represents a nonpermissive environment for the development of myeloid, natural killer (NK), and B-cells because the thymic epithelium offers the DLL1 and DLL4 ligands to the NOTCH1-expressing progenitor T-cells (Feyerabend et al. 2009; Schmitt et al. 2004a). Of note, Notch blocks the alternative differentiation

B. D. Giaimo et al.

pathways even if the cells are ectopically forced to express TFs required for differentiating versus other lineages (Franco et al. 2006; Laiosa et al. 2006).

Notch Signaling in Leukemia Given the key role of Notch signaling in T-cell differentiation, it is not surprising to observe aberrant regulation of the Notch pathways in T-cell leukemias. Mutations of the NOTCH1 gene have been identified in T-ALL patients and cell lines (Breit et al. 2006; Larson Gedman et al. 2009; Mansour et al. 2006; Palomero et al. 2006; Weng et  al. 2004). These mutations lead to increased activation of the pathway, and they can be classified into two different groups based on the molecular mechanism: mutations that lead to ligand-independent activation of the pathway and mutations that increase the half-life of the NICD proteins. The former include translocations that fuse the NICD-encoding sequences to another gene or mutations that influence the cleavage of the receptor, for example, mutations of the heterodimerization domain (HD) (Larson Gedman et  al. 2009; Malecki et  al. 2006; Weng et  al. 2004). The latter are mutations that result in C-terminal truncated NICD proteins lacking the PEST (proline, glutamic acid, serine, and threonine) domain which is required for the turnover of the NICD proteins (Larson Gedman et  al. 2009; Palomero et  al. 2006; Weng et  al. 2004). Mutations, although very rare, may also occur in the ankyrin repeats (ANKs) and in the transactivation domain (TAD) of NOTCH1  in T-ALL (Zhu et al. 2006). Importantly, hyperactivation of the Notch pathway can also be achieved compromising the activity of its negative regulators. In fact, mutations of the NOTCH1 E3-ubiquitin-ligase F-Box and WD repeat domain-containing 7 (FBXW7)encoding gene have been identified in T-ALL (Larson Gedman et  al. 2009). Additionally, upregulation of positive regulators of the Notch pathway can also lead to hyperactivation of the pathway. In line with this, MAML2 is upregulated in B-cell-derived lymphomas (Kochert et  al.

2  Transcription Factor RBPJ as a Molecular Switch in Regulating the Notch Response

2011) and was described fused to the lysine-­ specific methyltransferase 2A (KMT2A) gene in T-ALL as result of a chromosomal inversion (Metzler et al. 2008). However, the Notch pathway, via HES1, seems to have a tumor-­suppressive function in B-cell acute lymphoblastic leukemia [B-ALL (Kannan et al. 2011)]. Recently, activating NOTCH mutations of the PEST domain have been identified also in CLL (Fabbri et  al. 2011; Puente et  al. 2011). Interestingly, mutations of the 3´-UTR (untranslated region) of the NOTCH1 gene have also been identified in CLL leading to increased activation of the pathway (Puente et  al. 2015). Activating NOTCH1 mutations significantly correlates with Richter transformation and chemorefractory CLL, and they have been proposed as predictors of poor survival (Fabbri et al. 2011). In line with a role for Notch signaling in CLL, γ-secretase inhibitor (GSI) treatment of B-CLL cells reduces their survival by meaning of apoptosis (Rosati et  al. 2009). Similar conclusions were reached using antibodies directed against NOTCH receptors, and furthermore the same study observed that Notch signaling is involved in drug resistance (Nwabo Kamdje et  al. 2012). Of note, EGR2 (early growth response 2) mutations are frequently associated with NOTCH1 or FBXW7 mutations in CLL patients (Young et  al. 2017). The observation that active Notch signaling is detectable also in CLL cases that lack NOTCH1 mutations suggests that other mechanisms can be used to activate the pathway in this disease and imply Notch signaling as a more general deregulated pathway associated with CLL (Fabbri et al. 2017). In mantle cell lymphomas (MCL), activating mutations of the NOTCH1 gene map to the HDand PEST-encoding regions (Kridel et al. 2012), and recently a genome-wide study identified Notch targets and RBPJ-binding sites in MCL cell lines (Ryan et al. 2017). Similarly, truncating NOTCH2 mutations were detected in MCL and diffuse large B-cell lymphoma (DLBCL) with the latter also characterized by missense NOTCH2 mutations (Bea et al. 2013) and NOTCH1 mutations (Fabbri et  al. 2011). Activating NOTCH2 and NOTCH1 mutations were also described in


splenic marginal zone lymphomas (SMZL) as well as inactivating SHARP mutations and mutations of other components of the Notch pathway (Rossi et al. 2012). Mutations of the Notch pathway similar to the leukemia-associated ones have also been identified in solid tumors (Giaimo and Borggrefe 2018) marking the importance to develop new therapies aimed to target the Notch pathway. Aberrant regulation of the Notch signaling pathway was also linked to the AML characterized by the t(8;21)(q22/q22) translocation that fuses the AML1 (also known as RUNX1) gene to the ETO gene. AML1 encodes for a hematopoietic cell-specific TF which heterodimerizes with a non-DNA-binding protein called CBFβ [core-­ binding factor β (Ogawa et al. 1993a, b)], and it is essential for definitive hematopoietic development (Okada et  al. 1998; Okuda et  al. 1996; Wang et al. 1996). AML1 is characterized by an N-terminal Runt homology domain (RHD) which characterizes all members of the RUNX family (RUNX1, RUNX2, and RUNX3) and by a C-terminal TAD.  Both DNA binding and heterodimerization with CBFβ are mediated through the RHD, and the function of CBFβ is to increase the stability and the DNA-binding affinity of AML1 (Huang et al. 2001; Tahirov et al. 2001). On the other side, the ETO gene, highly expressed in the brain (Miyoshi et al. 1993) and in hematopoietic cells (Erickson et al. 1996), is the homolog of the Drosophila Nervy in four regions protein (Feinstein et al. 1995); in fact, it encodes for a non-DNA-binding protein characterized by four evolutionarily conserved functional domains called nervy homology regions (NHR): the NHR2 forms an amphipathic helix and it is important for homodimerization (Lutterbach et  al. 1998a) and heterodimerization with MTGR1 (Kitabayashi et  al. 1998); the NHR4 contains two putative zinc fingers (ZnF) required for interactions with NCoR and SMRT which links ETO to HDACs (Gelmetti et  al. 1998; Lutterbach et  al. 1998b; Wang et  al. 1998). Of note, the function of NHR4 is strongly dependent on NHR2 (Zhang et al. 2001). The t(8;21)(q22/q22) translocation fuses the DNA encoding the first N-terminal 177 residues


of AML1, which include the RHD, in frame with nearly all of ETO (Erickson et  al. 1992; Kozu et  al. 1993; Miyoshi et  al. 1993; Nisson et  al. 1992). This translocation leads to deletion of the C-terminal activation domain of AML1, and the resulting AML1/ETO (AE) protein acts as a dominant-­negative form of AML1, which binds to AML1-binding sites (Gardini et  al. 2008) repressing target genes (Frank et  al. 1995; Liu et  al. 2007). Of note, A/E expression requires additional mutations to induce leukemia in a murine in vivo model (Yuan et al. 2001), but this is not true for two different C-terminal truncated AE proteins [AML1/ETO 9a (AE9a) and AML1/ ETO truncated (AEtr)] which are potent inducers of leukemia in mice (Yan et al. 2009; Yan et al. 2004; Yan et  al. 2006). Interestingly, AE9a is deleted of NHR3 and NHR4, arguing against the well-accepted model that AE acts exclusively as a repressor of AML1 target genes (Heibert et al. 2001). The first evidence about an aberrant regulation of the Notch signaling pathway in AML came out with the observation that overexpression of AE leads to upregulation of the Notch target gene Hes1 (Alcalay et al. 2003). The underlying mechanism was unveiled when ETO was identified as a component of the RBPJ/SHARP corepressor complex (Salat et al. 2008). In detail, ETO and, surprisingly, AE directly interact with SHARP, but while ETO is able to augment SHARP-­ mediated repression, this is not the case for AE. Furthermore, knockdown of ETO or overexpression of AE resulted in activation of Notch target genes, suggesting that AE is able to derepress their expression, probably contributing to the oncogenic potential of AE in AML (Salat et al. 2008). In line with that, MTG16 which was also found fused to AML1 in cases of secondary AML cases (Gamou et  al. 1998) interacts with the RBPJ-associated corepressor complex, and this interaction is regulated in a Notch-dependent fashion (Engel et al. 2010). The exact role of CBFβ in the transformation process driven by AE remained unclear for a long time as two different studies arrived to opposite conclusions (Kwok et al. 2009, 2010; Park et al. 2009; Roudaia et al. 2009). Kwok and colleagues

B. D. Giaimo et al.

observed that the AE/CBFβ interaction is dispensable for leukemic transformation when CBFβ-interacting deficient AE mutants were retrovirally transduced into primary bone marrow cells (Kwok et  al. 2009, 2010). In contrast, the study from Roudaia and colleagues observed that this interaction is strongly required to induce leukemia (Park et al. 2009; Roudaia et al. 2009) and in support of that, inhibitors of the AE/CBFβ interaction reduce cell proliferation of the ME-1 cell line characterized by a chromosomal ­translocation that involves the CBFβ-encoding gene (Gorczynski et al. 2007). Our recent study helped to clarify these contradicting results. We designed CBFβ-interacting defective AE9a mutants, and upon retroviral transduction into HoxB4-immortalized hematopoietic progenitors, we observed that the AE/ CBFβ interaction is required to derepress Notch target genes but not to deregulate AML1 target genes (Thiel et  al. 2017). Furthermore, the AE/ CBFβ interaction is required for the colony-­ forming potential of transduced progenitors and to induce leukemia into recipient mice, and it must be noted that mice receiving the CBFβ-­ interacting defective AE9a mutant present only with myeloproliferative defects (Thiel et  al. 2017). These data suggest that AE9a deregulate AML1 targets independently of CBFβ leading to a myeloproliferative disease; however, the AE9a/ CBFβ interaction is required to deregulate Notch target genes and induce leukemia. While these data suggest that derepression of Notch signaling has an oncogenic role in AML, other studies observed the opposite in fact: Notch signaling has a tumor-suppressive role in AML cases that are not associated with the t(8;21) translocation (Kannan et  al. 2013; Lobry et  al. 2013). In this case, the tumor-suppressive role of Notch signaling seems to be dependent on the repressive activity of HES1 (Kannan et al. 2013; Tian et al. 2015b). In line with that, HES1 expression correlates with a better prognosis in AML cases characterized by CBFβ alterations (Tian et al. 2015a), and pharmacological activation of Notch signaling has a tumor-suppressive function (Ye et al. 2016). In mouse models of MLL/AF9 (mixed-lineage leukemia/ALL1-fused gene from

2  Transcription Factor RBPJ as a Molecular Switch in Regulating the Notch Response

chromosome 9 protein)-induced AML, HES1 has a tumor-suppressive role by promoting repression of FLT3 [FMS-like tyrosine kinase 3 (Kato et  al. 2015; Lobry et  al. 2013)]. Interestingly, Lobry and colleagues observed that Notch activation, in an AE background, has a tumor-­ suppressive role (Lobry et  al. 2013). The discrepancy observed between our study (Thiel et  al. 2017) and the study from Lobry and colleagues (Lobry et al. 2013) may be due to the different approaches used: while we only overexpressed AE9a leading to derepression, Lobry and colleagues overexpressed both AE and NICD2. In this way, the activation levels may bring the difference(s) between oncogenic and tumor-suppressive role for Notch signaling with a weak activation (derepression) having an oncogenic role and a stronger activation (given by the AE and the NICD2 together) having a tumor-­ suppressive role. Of note, also the fusion protein OTT/MAL [one twenty-two/megakaryocytic acute leukemia, also known as RBM15/MKL1 (RNA-­ binding motif protein 15/megakaryoblastic leukemia 1)], which is the result of the t(1;22)(p13;q13) translocation, was proposed to disturb the repressive function of RBPJ in acute megakaryoblastic leukemia [AMKL (Mercher et al. 2009)].

Conclusion and Outlook The function of the transcription factor RBPJ not only in the presence but also in the absence of Notch activation is of major importance, since this affects chromatin regulation and hence target specificity. It would be highly desirable to have novel compounds that specifically disrupt the RBPJ-corepressor function in certain disease settings like AML.  Similarly, compounds able to disrupt the activation function of RBPJ would be very helpful to avoid the serious off-target effects observed with γ-secretase inhibitors. In line with that, a recent study characterized a new RBPJ inhibitor that prevents both its repressive and activating function (Hurtado et  al. 2019). Chromatin regulation is to be expected at the center of RBPJ-mediated repressive mechanisms.


Acknowledgments  This work was supported by the collaborative research grant TRR81 and the Heisenberg program (BO 1639/5-1) by the DFG (German Research Foundation) and the Excellence Cluster for Cardio Pulmonary System (ECCPS) in Giessen to T.B. Funding for open access charge was provided by the DFG collaborative research TRR81. B.D.G. is supported by a Research Grant of the University Medical Center Giessen and Marburg (UKGM). Competing Interests  The authors declare that they have no competing interests. Consent for Publication  All authors have approved the manuscript.

References Alcalay M, Meani N, Gelmetti V, Fantozzi A, Fagioli M, Orleth A, Riganelli D, Sebastiani C, Cappelli E, Casciari C et  al (2003) Acute myeloid leukemia fusion proteins deregulate genes involved in stem cell maintenance and DNA repair. J Clin Invest 112:1751–1761 Arnett KL, Hass M, McArthur DG, Ilagan MX, Aster JC, Kopan R, Blacklow SC (2010) Structural and mechanistic insights into cooperative assembly of dimeric Notch transcription complexes. Nat Struct Mol Biol 17:1312–1317 Augert A, Eastwood E, Ibrahim AH, Wu N, Grunblatt E, Basom R, Liggitt D, Eaton KD, Martins R, Poirier JT et al (2019) Targeting NOTCH activation in small cell lung cancer through LSD1 inhibition. Sci Signal 12 Bea S, Valdes-Mas R, Navarro A, Salaverria I, Martin-­ Garcia D, Jares P, Gine E, Pinyol M, Royo C, Nadeu F et  al (2013) Landscape of somatic mutations and clonal evolution in mantle cell lymphoma. Proc Natl Acad Sci U S A 110:18250–18255 Borggrefe T, Liefke R (2012) Fine-tuning of the intracellular canonical Notch signaling pathway. Cell Cycle 11:264–276 Borggrefe T, Oswald F (2009) The Notch signaling pathway: transcriptional regulation at Notch target genes. Cell Mol Life Sci 66:1631–1646 Borggrefe T, Lauth M, Zwijsen A, Huylebroeck D, Oswald F, Giaimo BD (2016) The notch intracellular domain integrates signals from Wnt, Hedgehog, TGFbeta/ BMP and hypoxia pathways. Biochim Biophys Acta 1863:303–313 Bray SJ (2006) Notch signalling: a simple pathway becomes complex. Nat Rev Mol Cell Biol 7:678–689 Breit S, Stanulla M, Flohr T, Schrappe M, Ludwig WD, Tolle G, Happich M, Muckenthaler MU, Kulozik AE (2006) Activating NOTCH1 mutations predict favorable early treatment response and long-term outcome in childhood precursor T-cell lymphoblastic leukemia. Blood 108:1151–1157

24 Brou C, Logeat F, Lecourtois M, Vandekerckhove J, Kourilsky P, Schweisguth F, Israel A (1994) Inhibition of the DNA-binding activity of Drosophila suppressor of hairless and of its human homolog, KBF2/RBP-J kappa, by direct protein-protein interaction with Drosophila hairless. Genes Dev 8:2491–2503 Castel D, Mourikis P, Bartels SJ, Brinkman AB, Tajbakhsh S, Stunnenberg HG (2013) Dynamic binding of RBPJ is determined by Notch signaling status. Genes Dev 27:1059–1071 Collins KJ, Yuan Z, Kovall RA (2014) Structure and function of the CSL-KyoT2 corepressor complex: a negative regulator of Notch signaling. Structure 22:70–81 Di Stefano L, Walker JA, Burgio G, Corona DF, Mulligan P, Naar AM, Dyson NJ (2011) Functional antagonism between histone H3K4 demethylases in  vivo. Genes Dev 25:17–28 Dieguez-Hurtado R, Kato K, Giaimo BD, Nieminen-­ Kelha M, Arf H, Ferrante F, Bartkuhn M, Zimmermann T, Bixel MG, Eilken HM et  al (2019) Loss of the transcription factor RBPJ induces disease-promoting properties in brain pericytes. Nat Commun 10:2817 Dreval K, Lake RJ, Fan HY (2019) HDAC1 negatively regulates selective mitotic chromatin binding of the Notch effector RBPJ in a KDM5A-dependent manner. Nucleic Acids Res 47:4521–4538 Ellisen LW, Bird J, West DC, Soreng AL, Reynolds TC, Smith SD, Sklar J (1991) TAN-1, the human homolog of the Drosophila notch gene, is broken by chromosomal translocations in T lymphoblastic neoplasms. Cell 66:649–661 Engel ME, Nguyen HN, Mariotti J, Hunt A, Hiebert SW (2010) Myeloid translocation gene 16 (MTG16) interacts with Notch transcription complex components to integrate Notch signaling in hematopoietic cell fate specification. Mol Cell Biol 30:1852–1863 Erickson P, Gao J, Chang KS, Look T, Whisenant E, Raimondi S, Lasher R, Trujillo J, Rowley J, Drabkin H (1992) Identification of breakpoints in t(8;21) acute myelogenous leukemia and isolation of a fusion transcript, AML1/ETO, with similarity to Drosophila segmentation gene, runt. Blood 80:1825–1831 Erickson PF, Dessev G, Lasher RS, Philips G, Robinson M, Drabkin HA (1996) ETO and AML1 phosphoproteins are expressed in CD34+ hematopoietic progenitors: implications for t(8;21) leukemogenesis and monitoring residual disease. Blood 88:1813–1823 Fabbri G, Rasi S, Rossi D, Trifonov V, Khiabanian H, Ma J, Grunn A, Fangazio M, Capello D, Monti S et al (2011) Analysis of the chronic lymphocytic leukemia coding genome: role of NOTCH1 mutational activation. J Exp Med 208:1389–1401 Fabbri G, Holmes AB, Viganotti M, Scuoppo C, Belver L, Herranz D, Yan XJ, Kieso Y, Rossi D, Gaidano G et al (2017) Common nonmutational NOTCH1 activation in chronic lymphocytic leukemia. Proc Natl Acad Sci U S A 114:E2911–E2919 Falo-Sanjuan J, Lammers NC, Garcia HG, Bray SJ (2019) Enhancer priming enables fast and sustained transcrip-

B. D. Giaimo et al. tional responses to Notch signaling. Dev Cell 2019 Aug 19;50(4):411–425 Feinstein PG, Kornfeld K, Hogness DS, Mann RS (1995) Identification of homeotic target genes in Drosophila melanogaster including nervy, a proto-oncogene homologue. Genetics 140:573–586 Feyerabend TB, Terszowski G, Tietz A, Blum C, Luche H, Gossler A, Gale NW, Radtke F, Fehling HJ, Rodewald HR (2009) Deletion of Notch1 converts pro-T cells to dendritic cells and promotes thymic B cells by cell-­ extrinsic and cell-intrinsic mechanisms. Immunity 30:67–79 Fortini ME, Artavanis-Tsakonas S (1994) The suppressor of hairless protein participates in notch receptor signaling. Cell 79:273–282 Franco CB, Scripture-Adams DD, Proekt I, Taghon T, Weiss AH, Yui MA, Adams SL, Diamond RA, Rothenberg EV (2006) Notch/Delta signaling constrains reengineering of pro-T cells by PU.1. Proc Natl Acad Sci U S A 103:11993–11998 Frank R, Zhang J, Uchida H, Meyers S, Hiebert SW, Nimer SD (1995) The AML1/ETO fusion protein blocks transactivation of the GM-CSF promoter by AML1B. Oncogene 11:2667–2674 Friedmann DR, Wilson JJ, Kovall RA (2008) RAM-­ induced allostery facilitates assembly of a notch pathway active transcription complex. J Biol Chem 283:14781–14791 Fryer CJ, Lamar E, Turbachova I, Kintner C, Jones KA (2002) Mastermind mediates chromatin-specific transcription and turnover of the Notch enhancer complex. Genes Dev 16:1397–1411 Fryer CJ, White JB, Jones KA (2004) Mastermind recruits CycC:CDK8 to phosphorylate the Notch ICD and coordinate activation with turnover. Mol Cell 16:509–520 Gamou T, Kitamura E, Hosoda F, Shimizu K, Shinohara K, Hayashi Y, Nagase T, Yokoyama Y, Ohki M (1998) The partner gene of AML1 in t(16;21) myeloid malignancies is a novel member of the MTG8(ETO) family. Blood 91:4028–4037 Gardini A, Cesaroni M, Luzi L, Okumura AJ, Biggs JR, Minardi SP, Venturini E, Zhang DE, Pelicci PG, Alcalay M (2008) AML1/ETO oncoprotein is directed to AML1 binding regions and co-localizes with AML1 and HEB on its targets. PLoS Genet 4:e1000275 Geimer Le Lay AS, Oravecz A, Mastio J, Jung C, Marchal P, Ebel C, Dembele D, Jost B, Le Gras S, Thibault C et  al (2014) The tumor suppressor Ikaros shapes the repertoire of notch target genes in T cells. Sci Signal 7:ra28 Gelmetti V, Zhang J, Fanelli M, Minucci S, Pelicci PG, Lazar MA (1998) Aberrant recruitment of the nuclear receptor corepressor-histone deacetylase complex by the acute myeloid leukemia fusion partner ETO. Mol Cell Biol 18:7185–7191 Gevry N, Chan HM, Laflamme L, Livingston DM, Gaudreau L (2007) p21 transcription is regulated by differential localization of histone H2A.Z. Genes Dev 21:1869–1881

2  Transcription Factor RBPJ as a Molecular Switch in Regulating the Notch Response Gevry N, Hardy S, Jacques PE, Laflamme L, Svotelis A, Robert F, Gaudreau L (2009) Histone H2A.Z is essential for estrogen receptor signaling. Genes Dev 23:1522–1533 Giaimo BD, Borggrefe T (2018) Introduction to molecular mechanisms in Notch signal transduction and disease pathogenesis. Adv Exp Med Biol 1066:3–30 Giaimo BD, Ferrante F, Borggrefe T (2017a) Chromatin immunoprecipitation (ChIP) in mouse T-cell lines. J Vis Exp Giaimo BD, Oswald F, Borggrefe T (2017b) Dynamic chromatin regulation at Notch target genes. Transcription 8:61–66 Giaimo BD, Ferrante F, Vallejo DM, Hein K, Gutierrez-­ Perez I, Nist A, Stiewe T, Mittler G, Herold S, Zimmermann T et  al (2018) Histone variant H2A.Z deposition and acetylation directs the canonical Notch signaling response. Nucleic Acids Res 46:8197–8215 Giaimo BD, Ferrante F, Herchenrother A, Hake SB, Borggrefe T (2019) The histone variant H2A.Z in gene regulation. Epigenetics Chromatin 12:37 Gomez-Lamarca MJ, Falo-Sanjuan J, Stojnic R, Abdul Rehman S, Muresan L, Jones ML, Pillidge Z, Cerda-­ Moya G, Yuan Z, Baloul S et al (2018) Activation of the notch signaling pathway in vivo elicits changes in CSL nuclear dynamics. Dev Cell 44:611–623 e617 Gorczynski MJ, Grembecka J, Zhou Y, Kong Y, Roudaia L, Douvas MG, Newman M, Bielnicka I, Baber G, Corpora T et  al (2007) Allosteric inhibition of the protein-protein interaction between the leukemia-­ associated proteins Runx1 and CBFbeta. Chem Biol 14:1186–1197 Grossman SR, Johannsen E, Tong X, Yalamanchili R, Kieff E (1994) The Epstein-Barr virus nuclear antigen 2 transactivator is directed to response elements by the J kappa recombination signal binding protein. Proc Natl Acad Sci U S A 91:7568–7572 Guruharsha KG, Hori K, Obar RA, Artavanis-Tsakonas S (2014) Proteomic analysis of the Notch interactome. Methods Mol Biol 1187:181–192 Hamaguchi Y, Matsunami N, Yamamoto Y, Honjo T (1989) Purification and characterization of a protein that binds to the recombination signal sequence of the immunoglobulin J kappa segment. Nucleic Acids Res 17:9015–9026 Han H, Tanigaki K, Yamamoto N, Kuroda K, Yoshimoto M, Nakahata T, Ikuta K, Honjo T (2002) Inducible gene knockout of transcription factor recombination signal binding protein-J reveals its essential role in T versus B lineage decision. Int Immunol 14:637–645 Hass MR, Liow HH, Chen X, Sharma A, Inoue YU, Inoue T, Reeb A, Martens A, Fulbright M, Raju S et al (2015) SpDamID: marking DNA bound by protein complexes identifies Notch-dimer responsive enhancers. Mol Cell 59:685–697 Heibert SW, Lutterbach B, Durst K, Wang L, Linggi B, Wu S, Wood L, Amann J, King D, Hou Y (2001) Mechanisms of transcriptional repression by the t(8;21)-, t(12;21)-, and inv(16)-encoded fusion


proteins. Cancer Chemother Pharmacol 48(Suppl 1):S31–S34 Hein K, Mittler G, Cizelsky W, Kuhl M, Ferrante F, Liefke R, Berger IM, Just S, Strang JE, Kestler HA et  al (2015) Site-specific methylation of Notch1 controls the amplitude and duration of the Notch1 response. Sci Signal 8:ra30 Henkel T, Ling PD, Hayward SD, Peterson MG (1994) Mediation of Epstein-Barr virus EBNA2 transactivation by recombination signal-binding protein J kappa. Science 265:92–95 Ho DM, Guruharsha KG, Artavanis-Tsakonas S (2018) The Notch Interactome: complexity in signaling circuitry. Adv Exp Med Biol 1066:125–140 Huang G, Shigesada K, Ito K, Wee HJ, Yokomizo T, Ito Y (2001) Dimerization with PEBP2beta protects RUNX1/AML1 from ubiquitin-proteasome-mediated degradation. EMBO J 20:723–733 Hunt A, Fischer M, Engel ME, Hiebert SW (2011) Mtg16/ Eto2 contributes to murine T-cell development. Mol Cell Biol 31:2544–2551 Hurtado C, Safarova A, Smith M, Chung R, Bruyneel AAN, Gomez-Galeno J, Oswald F, Larson CJ, Cashman JR, Ruiz-Lozano P et al (2019) Disruption of NOTCH signaling by a small molecule inhibitor of the transcription factor RBPJ. Sci Rep 9:10811 Izon DJ, Aster JC, He Y, Weng A, Karnell FG, Patriub V, Xu L, Bakkour S, Rodriguez C, Allman D, Pear WS (2002) Deltex1 redirects lymphoid progenitors to the B cell lineage by antagonizing Notch1. Immunity 16:231–243 Jin K, Zhou W, Han X, Wang Z, Li B, Jeffries S, Tao W, Robbins DJ, Capobianco AJ (2017) Acetylation of mastermind-like 1 by p300 drives the recruitment of NACK to initiate Notch-dependent transcription. Cancer Res 77:4228–4237 Jung C, Mittler G, Oswald F, Borggrefe T (2013) RNA helicase Ddx5 and the noncoding RNA SRA act as coactivators in the Notch signaling pathway. Biochim Biophys Acta 1833:1180–1189 Kannan S, Fang W, Song G, Mullighan CG, Hammitt R, McMurray J, Zweidler-McKay PA (2011) Notch/ HES1-mediated PARP1 activation: a cell type-­ specific mechanism for tumor suppression. Blood 117:2891–2900 Kannan S, Sutphin RM, Hall MG, Golfman LS, Fang W, Nolo RM, Akers LJ, Hammitt RA, McMurray JS, Kornblau SM et  al (2013) Notch activation inhibits AML growth and survival: a potential therapeutic approach. J Exp Med 210:321–337 Kato T, Sakata-Yanagimoto M, Nishikii H, Ueno M, Miyake Y, Yokoyama Y, Asabe Y, Kamada Y, Muto H, Obara N et al (2015) Hes1 suppresses acute myeloid leukemia development through FLT3 repression. Leukemia 29:576–585 Kitabayashi I, Ida K, Morohoshi F, Yokoyama A, Mitsuhashi N, Shimizu K, Nomura N, Hayashi Y, Ohki M (1998) The AML1-MTG8 leukemic fusion protein forms a complex with a novel member of the

26 MTG8(ETO/CDR) family, MTGR1. Mol Cell Biol 18:846–858 Kitagawa M, Oyama T, Kawashima T, Yedvobnick B, Kumar A, Matsuno K, Harigaya K (2001) A human protein with sequence similarity to Drosophila mastermind coordinates the nuclear form of notch and a CSL protein to build a transcriptional activator complex on target promoters. Mol Cell Biol 21:4337–4346 Kochert K, Ullrich K, Kreher S, Aster JC, Kitagawa M, Johrens K, Anagnostopoulos I, Jundt F, Lamprecht B, Zimber-Strobl U et al (2011) High-level expression of Mastermind-like 2 contributes to aberrant activation of the NOTCH signaling pathway in human lymphomas. Oncogene 30:1831–1840 Kovall RA, Hendrickson WA (2004) Crystal structure of the nuclear effector of Notch signaling, CSL, bound to DNA. EMBO J 23:3441–3451 Kozu T, Miyoshi H, Shimizu K, Maseki N, Kaneko Y, Asou H, Kamada N, Ohki M (1993) Junctions of the AML1/MTG8(ETO) fusion are constant in t(8;21) acute myeloid leukemia detected by reverse transcription polymerase chain reaction. Blood 82:1270–1276 Krejci A, Bray S (2007) Notch activation stimulates transient and selective binding of Su(H)/CSL to target enhancers. Genes Dev 21:1322–1327 Kridel R, Meissner B, Rogic S, Boyle M, Telenius A, Woolcock B, Gunawardana J, Jenkins C, Cochrane C, Ben-Neriah S et  al (2012) Whole transcriptome sequencing reveals recurrent NOTCH1 mutations in mantle cell lymphoma. Blood 119:1963–1971 Kurooka H, Honjo T (2000) Functional interaction between the mouse notch1 intracellular region and histone acetyltransferases PCAF and GCN5. J Biol Chem 275:17211–17220 Kusch T, Florens L, Macdonald WH, Swanson SK, Glaser RL, Yates JR 3rd, Abmayr SM, Washburn MP, Workman JL (2004) Acetylation by Tip60 is required for selective histone variant exchange at DNA lesions. Science 306:2084–2087 Kwok C, Zeisig BB, Qiu J, Dong S, So CW (2009) Transforming activity of AML1-ETO is independent of CBFbeta and ETO interaction but requires formation of homo-oligomeric complexes. Proc Natl Acad Sci U S A 106:2853–2858 Kwok C, Zeisig BB, Dong S, So CW (2010) The role of CBFbeta in AML1-ETO's activity. Blood 115:3176–3177 Laiosa CV, Stadtfeld M, Xie H, de Andres-Aguayo L, Graf T (2006) Reprogramming of committed T cell progenitors to macrophages and dendritic cells by C/ EBP alpha and PU.1 transcription factors. Immunity 25:731–744 Larson Gedman A, Chen Q, Kugel Desmoulin S, Ge Y, LaFiura K, Haska CL, Cherian C, Devidas M, Linda SB, Taub JW, Matherly LH (2009) The impact of NOTCH1, FBW7 and PTEN mutations on prognosis and downstream signaling in pediatric T-cell acute lymphoblastic leukemia: a report from the Children’s Oncology Group. Leukemia 23:1417–1425

B. D. Giaimo et al. Liang Y, Chang J, Lynch SJ, Lukac DM, Ganem D (2002) The lytic switch protein of KSHV activates gene expression via functional interaction with RBP-Jkappa (CSL), the target of the Notch signaling pathway. Genes Dev 16:1977–1989 Liang L, Zhang HW, Liang J, Niu XL, Zhang SZ, Feng L, Liang YM, Han H (2008) KyoT3, an isoform of murine FHL1, associates with the transcription factor RBP-J and represses the RBP-J-mediated transactivation. Biochim Biophys Acta 1779:805–810 Liefke R, Oswald F, Alvarado C, Ferres-Marco D, Mittler G, Rodriguez P, Dominguez M, Borggrefe T (2010) Histone demethylase KDM5A is an integral part of the core Notch-RBP-J repressor complex. Genes Dev 24:590–601 Lin SE, Oyama T, Nagase T, Harigaya K, Kitagawa M (2002) Identification of new human mastermind proteins defines a family that consists of positive regulators for notch signaling. J Biol Chem 277:50612–50620 Lin S, Tian L, Shen H, Gu Y, Li JL, Chen Z, Sun X, You MJ, Wu L (2013) DDX5 is a positive regulator of oncogenic NOTCH1 signaling in T cell acute lymphoblastic leukemia. Oncogene 32:4845–4853 Ling PD, Rawlins DR, Hayward SD (1993) The Epstein-­ Barr virus immortalizing protein EBNA-2 is targeted to DNA by a cellular enhancer-binding protein. Proc Natl Acad Sci U S A 90:9237–9241 Liu Y, Chen W, Gaudet J, Cheney MD, Roudaia L, Cierpicki T, Klet RC, Hartman K, Laue TM, Speck NA, Bushweller JH (2007) Structural basis for recognition of SMRT/N-CoR by the MYND domain and its contribution to AML1/ETO's activity. Cancer Cell 11:483–497 Lobry C, Ntziachristos P, Ndiaye-Lobry D, Oh P, Cimmino L, Zhu N, Araldi E, Hu W, Freund J, Abdel-­ Wahab O et al (2013) Notch pathway activation targets AML-initiating cell homeostasis and differentiation. J Exp Med 210:301–319 Lutterbach B, Sun D, Schuetz J, Hiebert SW (1998a) The MYND motif is required for repression of basal transcription from the multidrug resistance 1 promoter by the t(8;21) fusion protein. Mol Cell Biol 18:3604–3611 Lutterbach B, Westendorf JJ, Linggi B, Patten A, Moniwa M, Davie JR, Huynh KD, Bardwell VJ, Lavinsky RM, Rosenfeld MG et al (1998b) ETO, a target of t(8;21) in acute leukemia, interacts with the N-CoR and mSin3 corepressors. Mol Cell Biol 18:7176–7184 Ma X, Renda MJ, Wang L, Cheng EC, Niu C, Morris SW, Chi AS, Krause DS (2007) Rbm15 modulates Notch-­ induced transcriptional activation and affects myeloid differentiation. Mol Cell Biol 27:3056–3064 Maillard I, Weng AP, Carpenter AC, Rodriguez CG, Sai H, Xu L, Allman D, Aster JC, Pear WS (2004) Mastermind critically regulates Notch-mediated lymphoid cell fate decisions. Blood 104:1696–1702 Malecki MJ, Sanchez-Irizarry C, Mitchell JL, Histen G, Xu ML, Aster JC, Blacklow SC (2006) Leukemia-­ associated mutations within the NOTCH1 heterodimerization domain fall into at least two distinct mechanistic classes. Mol Cell Biol 26:4642–4651

2  Transcription Factor RBPJ as a Molecular Switch in Regulating the Notch Response Mansour MR, Linch DC, Foroni L, Goldstone AH, Gale RE (2006) High incidence of Notch-1 mutations in adult patients with T-cell acute lymphoblastic leukemia. Leukemia 20:537–539 Mercher T, Raffel GD, Moore SA, Cornejo MG, Baudry-­ Bluteau D, Cagnard N, Jesneck JL, Pikman Y, Cullen D, Williams IR et  al (2009) The OTT-MAL fusion oncogene activates RBPJ-mediated transcription and induces acute megakaryoblastic leukemia in a knockin mouse model. J Clin Invest 119:852–864 Metzler M, Staege MS, Harder L, Mendelova D, Zuna J, Fronkova E, Meyer C, Flohr T, Bednarova D, Harbott J et al (2008) Inv(11)(q21q23) fuses MLL to the Notch co-activator mastermind-like 2  in secondary T-cell acute lymphoblastic leukemia. Leukemia 22:1807–1811 Mikami S, Kanaba T, Ito Y, Mishima M (2013) NMR assignments of SPOC domain of the human transcriptional corepressor SHARP in complex with a C-terminal SMRT peptide. Biomol NMR Assign 7:267–270 Mikami S, Kanaba T, Takizawa N, Kobayashi A, Maesaki R, Fujiwara T, Ito Y, Mishima M (2014) Structural insights into the recruitment of SMRT by the corepressor SHARP under phosphorylative regulation. Structure 22:35–46 Miyoshi H, Kozu T, Shimizu K, Enomoto K, Maseki N, Kaneko Y, Kamada N, Ohki M (1993) The t(8;21) translocation in acute myeloid leukemia results in production of an AML1-MTG8 fusion transcript. EMBO J 12:2715–2721 Moshkin YM, Kan TW, Goodfellow H, Bezstarosti K, Maeda RK, Pilyugin M, Karch F, Bray SJ, Demmers JA, Verrijzer CP (2009) Histone chaperones ASF1 and NAP1 differentially modulate removal of active histone marks by LID-RPD3 complexes during NOTCH silencing. Mol Cell 35:782–793 Mulligan P, Yang F, Di Stefano L, Ji JY, Ouyang J, Nishikawa JL, Toiber D, Kulkarni M, Wang Q, Najafi-­ Shoushtari SH et al (2011) A SIRT1-LSD1 corepressor complex regulates Notch target gene expression and development. Mol Cell 42:689–699 Nam Y, Sliz P, Song L, Aster JC, Blacklow SC (2006) Structural basis for cooperativity in recruitment of MAML coactivators to Notch transcription complexes. Cell 124:973–983 Nam Y, Sliz P, Pear WS, Aster JC, Blacklow SC (2007) Cooperative assembly of higher-order Notch complexes functions as a switch to induce transcription. Proc Natl Acad Sci U S A 104:2103–2108 Nisson PE, Watkins PC, Sacchi N (1992) Transcriptionally active chimeric gene derived from the fusion of the AML1 gene and a novel gene on chromosome 8  in t(8;21) leukemic cells. Cancer Genet Cytogenet 63:81–88 Nwabo Kamdje AH, Bassi G, Pacelli L, Malpeli G, Amati E, Nichele I, Pizzolo G, Krampera M (2012) Role of stromal cell-mediated Notch signaling in CLL resistance to chemotherapy. Blood Cancer J 2:e73 Ogawa E, Inuzuka M, Maruyama M, Satake M, Naito-­ Fujimoto M, Ito Y, Shigesada K (1993a) Molecular cloning and characterization of PEBP2 beta, the


heterodimeric partner of a novel Drosophila runt-­ related DNA binding protein PEBP2 alpha. Virology 194:314–331 Ogawa E, Maruyama M, Kagoshima H, Inuzuka M, Lu J, Satake M, Shigesada K, Ito Y (1993b) PEBP2/ PEA2 represents a family of transcription factors ­homologous to the products of the Drosophila runt gene and the human AML1 gene. Proc Natl Acad Sci U S A 90:6859–6863 Okada H, Watanabe T, Niki M, Takano H, Chiba N, Yanai N, Tani K, Hibino H, Asano S, Mucenski ML et  al (1998) AML1(−/−) embryos do not express certain hematopoiesis-related gene transcripts including those of the PU.1 gene. Oncogene 17:2287–2293 Okuda T, van Deursen J, Hiebert SW, Grosveld G, Downing JR (1996) AML1, the target of multiple chromosomal translocations in human leukemia, is essential for normal fetal liver hematopoiesis. Cell 84:321–330 Oswald F, Kovall RA (2018) CSL-associated corepressor and coactivator complexes. Adv Exp Med Biol 1066:279–295 Oswald F, Tauber B, Dobner T, Bourteele S, Kostezka U, Adler G, Liptay S, Schmid RM (2001) p300 acts as a transcriptional coactivator for mammalian Notch-1. Mol Cell Biol 21:7761–7774 Oswald F, Kostezka U, Astrahantseff K, Bourteele S, Dillinger K, Zechner U, Ludwig L, Wilda M, Hameister H, Knochel W et  al (2002) SHARP is a novel component of the Notch/RBP-Jkappa signalling pathway. EMBO J 21:5417–5426 Oswald F, Winkler M, Cao Y, Astrahantseff K, Bourteele S, Knochel W, Borggrefe T (2005) RBP-Jkappa/SHARP recruits CtIP/CtBP corepressors to silence Notch target genes. Mol Cell Biol 25:10379–10390 Oswald F, Rodriguez P, Giaimo BD, Antonello ZA, Mira L, Mittler G, Thiel VN, Collins KJ, Tabaja N, Cizelsky W et  al (2016) A phospho-dependent mechanism involving NCoR and KMT2D controls a permissive chromatin state at Notch target genes. Nucleic Acids Res 44:4703–4720 Palomero T, Barnes KC, Real PJ, Glade Bender JL, Sulis ML, Murty VV, Colovai AI, Balbin M, Ferrando AA (2006) CUTLL1, a novel human T-cell lymphoma cell line with t(7;9) rearrangement, aberrant NOTCH1 activation and high sensitivity to gamma-secretase inhibitors. Leukemia 20:1279–1287 Park S, Speck NA, Bushweller JH (2009) The role of CBFbeta in AML1-ETO's activity. Blood 114:2849–2850 Pear WS, Aster JC, Scott ML, Hasserjian RP, Soffer B, Sklar J, Baltimore D (1996) Exclusive development of T cell neoplasms in mice transplanted with bone marrow expressing activated Notch alleles. J Exp Med 183:2283–2291 Petrovic J, Zhou Y, Fasolino M, Goldman N, Schwartz GW, Mumbach MR, Nguyen SC, Rome KS, Sela Y, Zapataro Z et  al (2019) Oncogenic Notch promotes long-range regulatory interactions within Hyperconnected 3D cliques. Mol Cell 2019 Mar 21;73(6):1174–1190

28 Pillidge Z, Bray SJ (2019) SWI/SNF chromatin remodeling controls Notch-responsive enhancer accessibility. EMBO Rep 2019 May;20(5):e46944 Pitulescu ME, Schmidt I, Giaimo BD, Antoine T, Berkenfeld F, Ferrante F, Park H, Ehling M, Biljes D, Rocha SF et  al (2017) Dll4 and notch signalling couples sprouting angiogenesis and artery formation. Nat Cell Biol 19:915–927 Puente XS, Pinyol M, Quesada V, Conde L, Ordonez GR, Villamor N, Escaramis G, Jares P, Bea S, Gonzalez-­ Diaz M et al (2011) Whole-genome sequencing identifies recurrent mutations in chronic lymphocytic leukaemia. Nature 475:101–105 Puente XS, Bea S, Valdes-Mas R, Villamor N, Gutierrez-­ Abril J, Martin-Subero JI, Munar M, Rubio-Perez C, Jares P, Aymerich M et al (2015) Non-coding recurrent mutations in chronic lymphocytic leukaemia. Nature 526:519–524 Pui JC, Allman D, Xu L, DeRocco S, Karnell FG, Bakkour S, Lee JY, Kadesch T, Hardy RR, Aster JC, Pear WS (1999) Notch1 expression in early lymphopoiesis influences B versus T lineage determination. Immunity 11:299–308 Radtke F, Wilson A, Stark G, Bauer M, van Meerwijk J, MacDonald HR, Aguet M (1999) Deficient T cell fate specification in mice with an induced inactivation of Notch1. Immunity 10:547–558 Rosati E, Sabatini R, Rampino G, Tabilio A, Di Ianni M, Fettucciari K, Bartoli A, Coaccioli S, Screpanti I, Marconi P (2009) Constitutively activated Notch signaling is involved in survival and apoptosis resistance of B-CLL cells. Blood 113:856–865 Rossi D, Trifonov V, Fangazio M, Bruscaggin A, Rasi S, Spina V, Monti S, Vaisitti T, Arruga F, Fama R et  al (2012) The coding genome of splenic marginal zone lymphoma: activation of NOTCH2 and other pathways regulating marginal zone development. J Exp Med 209:1537–1551 Roudaia L, Cheney MD, Manuylova E, Chen W, Morrow M, Park S, Lee CT, Kaur P, Williams O, Bushweller JH, Speck NA (2009) CBFbeta is critical for AML1-­ ETO and TEL-AML1 activity. Blood 113:3070–3079 Ryan RJH, Petrovic J, Rausch DM, Zhou Y, Lareau CA, Kluk MJ, Christie AL, Lee WY, Tarjan DR, Guo B et al (2017) A B cell Regulome links Notch to downstream oncogenic pathways in small B cell lymphomas. Cell Rep 21:784–797 Salat D, Liefke R, Wiedenmann J, Borggrefe T, Oswald F (2008) ETO, but not leukemogenic fusion protein AML1/ETO, augments RBP-Jkappa/SHARP-­ mediated repression of notch target genes. Mol Cell Biol 28:3502–3512 Schmitt TM, Zuniga-Pflucker JC (2002) Induction of T cell development from hematopoietic progenitor cells by delta-like-1 in vitro. Immunity 17:749–756 Schmitt TM, Ciofani M, Petrie HT, Zuniga-Pflucker JC (2004a) Maintenance of T cell specification and differentiation requires recurrent notch receptor-ligand interactions. J Exp Med 200:469–479 Schmitt TM, de Pooter RF, Gronski MA, Cho SK, Ohashi PS, Zuniga-Pflucker JC (2004b) Induction of T cell

B. D. Giaimo et al. development and establishment of T cell competence from embryonic stem cells differentiated in vitro. Nat Immunol 5:410–417 Severson E, Arnett KL, Wang H, Zang C, Taing L, Liu H, Pear WS, Shirley Liu X, Blacklow SC, Aster JC (2017) Genome-wide identification and characterization of Notch transcription complex-binding sequence-paired sites in leukemia cells. Sci Signal 2017 May 2;10(477):eaag1598 Skalska L, Stojnic R, Li J, Fischer B, Cerda-Moya G, Sakai H, Tajbakhsh S, Russell S, Adryan B, Bray SJ (2015) Chromatin signatures at Notch-regulated enhancers reveal large-scale changes in H3K56ac upon activation. EMBO J 34:1889–1904 Tabaja N, Yuan Z, Oswald F, Kovall RA (2017) Structure-function analysis of RBP-J-interacting and tubulin-associated (RITA) reveals regions critical for repression of Notch target genes. J Biol Chem 292:10549–10563 Tahirov TH, Inoue-Bungo T, Morii H, Fujikawa A, Sasaki M, Kimura K, Shiina M, Sato K, Kumasaka T, Yamamoto M et al (2001) Structural analyses of DNA recognition by the AML1/Runx-1 Runt domain and its allosteric control by CBFbeta. Cell 104:755–767 Taniguchi Y, Furukawa T, Tun T, Han H, Honjo T (1998) LIM protein KyoT2 negatively regulates transcription by association with the RBP-J DNA-binding protein. Mol Cell Biol 18:644–654 Terriente-Felix A, Li J, Collins S, Mulligan A, Reekie I, Bernard F, Krejci A, Bray S (2013) Notch cooperates with Lozenge/Runx to lock haemocytes into a differentiation programme. Development 140:926–937 Tetzlaff F, Fischer A (2018) Control of blood vessel formation by Notch signaling. Adv Exp Med Biol 1066:319–338 Thiel VN, Giaimo BD, Schwarz P, Soller K, Vas V, Bartkuhn M, Blatte TJ, Dohner K, Bullinger L, Borggrefe T et al (2017) Heterodimerization of AML1/ ETO with CBFbeta is required for leukemogenesis but not for myeloproliferation. Leukemia 31:2491–2502 Tian C, Tang Y, Wang T, Yu Y, Wang X, Wang Y, Zhang Y (2015a) HES1 is an independent prognostic factor for acute myeloid leukemia. Onco Targets Ther 8:899–904 Tian C, Yu Y, Jia Y, Zhu L, Zhang Y (2015b) HES1 activation suppresses proliferation of leukemia cells in acute myeloid leukemia. Ann Hematol 94:1477–1483 Tottone L, Zhdanovskaya N, Carmona Pestana A, Zampieri M, Simeoni F, Lazzari S, Ruocco V, Pelullo M, Caiafa P, Felli MP et al (2019) Histone modifications drive aberrant Notch3 expression/activity and growth in T-ALL. Front Oncol 9:198 Tun T, Hamaguchi Y, Matsunami N, Furukawa T, Honjo T, Kawaichi M (1994) Recognition sequence of a highly conserved DNA binding protein RBP-J kappa. Nucleic Acids Res 22:965–971 Vijayaraghavan J, Osborne BA (2018) Notch and T cell function  – a complex tale. Adv Exp Med Biol 1066:339–354 Wacker SA, Alvarado C, von Wichert G, Knippschild U, Wiedenmann J, Clauss K, Nienhaus GU, Hameister H,

2  Transcription Factor RBPJ as a Molecular Switch in Regulating the Notch Response Baumann B, Borggrefe T et al (2011) RITA, a novel modulator of Notch signalling, acts via nuclear export of RBP-J. EMBO J 30:43–56 Wallberg AE, Pedersen K, Lendahl U, Roeder RG (2002) p300 and PCAF act cooperatively to mediate transcriptional activation from chromatin templates by notch intracellular domains in  vitro. Mol Cell Biol 22:7812–7819 Waltzer L, Logeat F, Brou C, Israel A, Sergeant A, Manet E (1994) The human J kappa recombination signal sequence binding protein (RBP-J kappa) targets the Epstein-Barr virus EBNA2 protein to its DNA responsive elements. EMBO J 13:5633–5638 Wang Q, Stacy T, Binder M, Marin-Padilla M, Sharpe AH, Speck NA (1996) Disruption of the Cbfa2 gene causes necrosis and hemorrhaging in the central nervous system and blocks definitive hematopoiesis. Proc Natl Acad Sci U S A 93:3444–3449 Wang J, Hoshino T, Redner RL, Kajigaya S, Liu JM (1998) ETO, fusion partner in t(8;21) acute myeloid leukemia, represses transcription by interaction with the human N-CoR/mSin3/HDAC1 complex. Proc Natl Acad Sci U S A 95:10860–10865 Wang H, Zou J, Zhao B, Johannsen E, Ashworth T, Wong H, Pear WS, Schug J, Blacklow SC, Arnett KL et al (2011) Genome-wide analysis reveals conserved and divergent features of Notch1/RBPJ binding in human and murine T-lymphoblastic leukemia cells. Proc Natl Acad Sci U S A 108:14908–14913 Wang H, Zang C, Taing L, Arnett KL, Wong YJ, Pear WS, Blacklow SC, Liu XS, Aster JC (2014) NOTCH1-­ RBPJ complexes drive target gene expression through dynamic interactions with superenhancers. Proc Natl Acad Sci U S A 111:705–710 Weaver KL, Alves-Guerra MC, Jin K, Wang Z, Han X, Ranganathan P, Zhu X, DaSilva T, Liu W, Ratti F et  al (2014) NACK is an integral component of the Notch transcriptional activation complex and is critical for development and tumorigenesis. Cancer Res 74:4741–4751 Weng AP, Ferrando AA, Lee W, Morris JP t, Silverman LB, Sanchez-Irizarry C, Blacklow SC, Look AT, Aster JC (2004) Activating mutations of NOTCH1 in human T cell acute lymphoblastic leukemia. Science 306:269–271 Wilson JJ, Kovall RA (2006) Crystal structure of the CSL-Notch-Mastermind ternary complex bound to DNA. Cell 124:985–996 Wilson A, MacDonald HR, Radtke F (2001) Notch 1-­deficient common lymphoid precursors adopt a B cell fate in the thymus. J Exp Med 194:1003–1012 Wu L, Aster JC, Blacklow SC, Lake R, Artavanis-­ Tsakonas S, Griffin JD (2000) MAML1, a human homologue of Drosophila mastermind, is a transcriptional co-activator for NOTCH receptors. Nat Genet 26:484–489 Wu L, Sun T, Kobayashi K, Gao P, Griffin JD (2002) Identification of a family of mastermind-like transcriptional coactivators for mammalian notch receptors. Mol Cell Biol 22:7688–7700


Xie Q, Wu Q, Kim L, Miller TE, Liau BB, Mack SC, Yang K, Factor DC, Fang X, Huang Z et  al (2016) RBPJ maintains brain tumor-initiating cells through CDK9-­ mediated transcriptional elongation. J Clin Invest 126:2757–2772 Xu T, Park SS, Giaimo BD, Hall D, Ferrante F, Ho DM, Hori K, Anhezini L, Ertl I, Bartkuhn M et  al (2017) RBPJ/CBF1 interacts with L3MBTL3/MBT1 to promote repression of Notch signaling via histone demethylase KDM1A/LSD1. EMBO J 36:3232–3249 Yan M, Burel SA, Peterson LF, Kanbe E, Iwasaki H, Boyapati A, Hines R, Akashi K, Zhang DE (2004) Deletion of an AML1-ETO C-terminal NcoR/SMRT-­ interacting region strongly induces leukemia development. Proc Natl Acad Sci U S A 101:17186–17191 Yan M, Kanbe E, Peterson LF, Boyapati A, Miao Y, Wang Y, Chen IM, Chen Z, Rowley JD, Willman CL, Zhang DE (2006) A previously unidentified alternatively spliced isoform of t(8;21) transcript promotes leukemogenesis. Nat Med 12:945–949 Yan M, Ahn EY, Hiebert SW, Zhang DE (2009) RUNX1/ AML1 DNA-binding domain and ETO/MTG8 NHR2-­ dimerization domain are critical to AML1-ETO9a leukemogenesis. Blood 113:883–886 Yashiro-Ohtani Y, Wang H, Zang C, Arnett KL, Bailis W, Ho Y, Knoechel B, Lanauze C, Louis L, Forsyth KS et al (2014) Long-range enhancer activity determines Myc sensitivity to Notch inhibitors in T cell leukemia. Proc Natl Acad Sci U S A 111:E4946–E4953 Yatim A, Benne C, Sobhian B, Laurent-Chabalier S, Deas O, Judde JG, Lelievre JD, Levy Y, Benkirane M (2012) NOTCH1 nuclear interactome reveals key regulators of its transcriptional activity and oncogenic function. Mol Cell 48:445–458 Ye Q, Jiang J, Zhan G, Yan W, Huang L, Hu Y, Su H, Tong Q, Yue M, Li H et al (2016) Small molecule activation of NOTCH signaling inhibits acute myeloid leukemia. Sci Rep 6:26510 Yoo JY, Choi HK, Choi KC, Park SY, Ota I, Yook JI, Lee YH, Kim K, Yoon HG (2012) Nuclear hormone receptor corepressor promotes esophageal cancer cell invasion by transcriptional repression of interferon-­ gamma-­ inducible protein 10  in a casein kinase 2-dependent manner. Mol Biol Cell 23:2943–2954 Yoo JY, Lim BJ, Choi HK, Hong SW, Jang HS, Kim C, Chun KH, Choi KC, Yoon HG (2013) CK2-NCoR signaling cascade promotes prostate tumorigenesis. Oncotarget 4:972–983 Young E, Noerenberg D, Mansouri L, Ljungstrom V, Frick M, Sutton LA, Blakemore SJ, Galan-Sousa J, Plevova K, Baliakas P et  al (2017) EGR2 mutations define a new clinically aggressive subgroup of chronic lymphocytic leukemia. Leukemia 31:1547–1554 Yuan Y, Zhou L, Miyamoto T, Iwasaki H, Harakawa N, Hetherington CJ, Burel SA, Lagasse E, Weissman IL, Akashi K, Zhang DE (2001) AML1-ETO expression is directly involved in the development of acute myeloid leukemia in the presence of additional mutations. Proc Natl Acad Sci U S A 98:10398–10403

30 Yuan Z, VanderWielen BD, Giaimo BD, Pan L, Collins CE, Turkiewicz A, Hein K, Oswald F, Borggrefe T, Kovall RA (2019) Structural and functional studies  of  the RBPJ-SHARP complex reveal a conserved corepressor binding site. Cell Rep 26:845–854 e846 Zhang J, Hug BA, Huang EY, Chen CW, Gelmetti V, Maccarana M, Minucci S, Pelicci PG, Lazar MA (2001) Oligomerization of ETO is obligatory for corepressor interaction. Mol Cell Biol 21:156–163 Zhao B, Zou J, Wang H, Johannsen E, Peng CW, Quackenbush J, Mar JC, Morton CC, Freedman ML, Blacklow SC et al (2011) Epstein-Barr virus exploits intrinsic B-lymphocyte transcription programs to

B. D. Giaimo et al. achieve immortal cell growth. Proc Natl Acad Sci U S A 108:14902–14907 Zhu YM, Zhao WL, Fu JF, Shi JY, Pan Q, Hu J, Gao XD, Chen B, Li JM, Xiong SM et  al (2006) NOTCH1 mutations in T-cell acute lymphoblastic leukemia: prognostic significance and implication in multifactorial leukemogenesis. Clin Cancer Res 12:3043–3049 Zimber-Strobl U, Strobl LJ, Meitinger C, Hinrichs R, Sakai T, Furukawa T, Honjo T, Bornkamm GW (1994) Epstein-Barr virus nuclear antigen 2 exerts its transactivating function through interaction with recombination signal binding protein RBP-J kappa, the homologue of Drosophila Suppressor of Hairless. EMBO J 13:4973–4982


Unravelling of Hidden Secrets: The Tumour Suppressor Lethal (2) Giant Discs (Lgd)/CC2D1, Notch Signalling and Cancer Tobias Reiff, Miriam Baeumers, Christine Tibbe, and Thomas Klein



The endosomal pathway plays a pivotal role upon signal transduction in the Notch pathway. Recent work on lethal (2) giant discs (lgd) points to an additional critical role in avoiding uncontrolled ligand-independent signalling during trafficking of the Notch receptor through the endosomal pathway to the lysosome for degradation. In this chapter, we will outline the journey of Notch through the endosomal system and present an overview of the current knowledge about Lgd and its mammalian orthologs Lgd1/CC2D1b and Lgd2/ CC2D1a. We will then discuss how Notch is activated in the absence of lgd function in Drosophila and ask whether there is evidence that a similar ligand-independent activation of the Notch pathway can also happen in mammals if the orthologs are inactivated.

The Notch pathway is one of a handful evolutionary conserved signalling systems that mediate communication among cells during development and tissue homeostasis in all metazoans. At its core, it is a simple pathway that consists of three core components, the ligands, the Notch receptor and a nuclear factor of the CSL family (an acronym for CBF-1/RBPJ-κ of Homo sapiens/Mus musculus, Suppressor of Hairless of Drosophila melanogaster and Lag-1 of Caenorhabditis elegans) (e.g. reviewed in Kovall et al. (2017)). In Drosophila, in which the pathway was discovered, two ligands, termed Delta (Dl) and Serrate (Ser), a single Notch receptor and one CSL factor, termed Suppressor of Hairless (Su(H)), exist. Notch ligands are transmembrane proteins, thus reaching neighbouring cells only, making Notch signalling the main pathway to mediate short-­ range communication. Signal transduction is initiated by binding of the ligand to Notch, which elicits two proteolytic cleavages (for a simple overview, see Fig. 3.1). The result is the release of the intracellular domain of Notch (NICD) into the cytosol and its subsequent transport into the nucleus. There, it associates with CSL and co-­ factors, such as Mastermind (Mam) to initiate transcription of the target genes. Thus, in essence Notch is a transcriptional regulator initially tethered to the membrane as a surface receptor that is released upon the presence of a signal protein.


Notch signalling · Lgd · Endosomal pathway · CC2D1A · CC2D1B · ESCRT · Shrub/ CHMP4 · Aki · FREUD-1 · FREUD-2 · TAPE T. Reiff · M. Baeumers · C. Tibbe · T. Klein (*) Institut fuer Genetik, Heinrich-Heine-Universitaet Duesseldorf, Duesseldorf, Germany e-mail: [email protected]; [email protected]; [email protected]; [email protected]

© Springer Nature Switzerland AG 2021 J. Reichrath, S. Reichrath (eds.), Notch Signaling in Embryology and Cancer, Advances in Experimental Medicine and Biology 1287,



T. Reiff et al.

Fig. 3.1  A simplified view of the Notch signalling pathway. The binding of a DSL ligand to Notch and its subsequent endocytosis elicits a conformational change in Notch. This change releases Notch from autoinhibition via its NRR domain and allows the S2 cleavage via Kuz/ ADAM10. The resulting intermediate (NEXT) is immedi-

ately cleaved by the γ-secretase complex to release NICD into the cytosol. NICD travels to the nucleus to assemble a transcriptional activator complex around CSL to activate the target genes. In the absence of a Notch activity, CSL associates with transcriptional co-repressors to actively suppress the expression of the target genes

Notch receptors are heterodimers whose two parts arise from the cleavage of a long precursor in the Golgi apparatus by a furin protease (reviewed in Arnett et al. (2018)). This S1 cleavage occurs in the extracellular part, located shortly behind the transmembrane domain. The two emerging parts are joint together via a salt bridge between Ca2+ and cysteine in the heterodimerisation domain (HD). The mammalian genome contains four Notch receptors, five ligands and one CSL factor. Three orthologs of Dl exist, termed Dl-like (DLL) 1, 3 and 4, and two of Ser, termed Jagged (JAG) 1 and 2. Notch receptors are large type I transmembrane proteins that, in addition to the HD, share a number of motifs in their extra- and intracellular domains (abbreviated ECD and ICD, respectively). The ECD contains 29–36 repeats of the EGF-like motif followed by the negative regula-

tory region (NRR), which is crucial for autoinhibition of the receptor in the absence of ligands. The NRR comprises the HD and three adjacent LIN12/Notch repeats (LNR), which are wrapped around the cleavage site for the ADAM10 protease performing the first of two activating cleavages, termed S2. In the autoinhibited state, the S2 cleavage site is obscured by the LNRs and becomes accessible during activation by a conformational change elicited by ligand pulling force. This pulling force is created through endocytosis of the ligand into the signal-emitting cell (Fig. 3.1). The resulting membrane-inserted fragment is termed Notch extracellular truncation (NEXT), which is immediately cleaved in its transmembrane domain by the γ-secretase complex (S3 cleavage). Importantly for this chapter, the S3 cleavage is relatively unspecific, since it has been shown that γ-secretase cleaves all Notch variants with a small ECD (below 150 amino

3  Unravelling of Hidden Secrets: The Tumour Suppressor Lethal (2) Giant Discs (Lgd)/CC2D1, Notch…

acids), even if the ECD or the transmembrane domain is replaced by an unrelated peptide sequence (Struhl and Adachi 2000). Hence, also NEXT-like variants will be efficiently cleaved by γ-secretase to release NICD. The S3 cleavage can potentially occur at the plasma membrane as well as in endosomal compartments or the lysosome, as γ-secretase is present in all these cell compartments (Vaccari et al. 2008; Pasternak et al. 2003). All canonical Notch ligands belong to the Delta/Serrate/Lag2 (DSL) family which share several structural features. The ECD contains a module at the N-terminus of Notch ligands (MNNL) and Delta/Serrate/LAG-2 (DSL) domain in their N-terminus followed by a stretch of multiple repeats of the EGF-like motifs (Arnett et al. 2018). They possess relatively short ICDs, which appear to be unstructured and share no obvious sequence similarity, except short stretches that serve as binding epitopes for two E3 ligases (Weinmaster and Fischer 2011). These E3 ligases, termed Mindbomb1 (Mib1) and Neuralized (Neur) in Drosophila, bind and ubiquitylate the ICDs of the ligands at distinct lysins (Ks). Orthologs exist in mammals termed Mindbomb1 (MIB1) and Neuralized-like 1 and 2 (Neurl1, 2), respectively. The ubiquitylation (ubi) is thought to elicit the endocytosis of the ligands that in turn creates the pulling force required to release Notch from autoinhibition. Experiments in Drosophila showed that, in contrast to Ser, Dl can also weakly signal in the absence of ubi by the E3 ligases (Berndt et al. 2017). Remarkably, the weak ubi-independent signal of Dl appears to be sufficient for developmental processes, such as neurogenesis, to occur without gross defects. Recent work indicates that Neur activates Dl mainly in an ubi-independent manner (Berndt et al. 2017). MIB1 simultaneously binds to two epitopes in the ICD of JAG1 and Dl, termed N- and C-Box, via its MZM and REP domains, respectively (Daskalaki et  al. 2011; McMillan et  al. 2015). The binding is a prerequisite for ubi and full activity of the ligand. Neur binds to a separate short stretch in the ICD of Dl and Ser, closer to the membrane with the consensus sequence NxxN (Fontana and Posakony 2009).


The target genes activated by the Notch pathway are tissue and context specific, and only few targets can be classified as general targets, among them genes of the HES/HER family of transcription factors; Nrarp, a negative regulator of the NICD/CSL transcription complex; and the transcriptional regulator Myc. Myc is a powerful common positive regulator of cell proliferation and an important driver of malignant transformation in several Notch-induced cancers (e.g. see Aster et al. (2017) for more details). Previous work established that the Notch pathway can be activated also in more unconventional manners in mammals, e.g. by non-­ canonical ligands or in a ligand-independent manner upon its travel through the endosomal pathway. Examples of non-canonical ligands are MAGP1/2, DLK1 and YB1 (see Siebel and Lendahl (2017) and citations therein).

Endosomal Trafficking of Notch Despite its role during ligand-dependent signalling, the endosomal pathway controls Notch activity by (i) degrading nonactivated Notch receptor, (ii) regulating receptor abundance on the cell surface and (iii) also in the generation of ligand-independent Notch signal. For an excellent overview of the pathway, the reader is referred to Huotari and Helenius (2011). An overview of the endosomal pathway and the journey of Notch therein is shown in Fig.  3.2. Notch is constantly endocytosed from the cell surface in a ligand-independent manner in all model systems (Chastagner et al. 2017; Jekely and Rorth 2003; Vaccari et  al. 2008; Windler and Bilder 2010; Schnute et al. 2018). The presence at the plasma membrane is therefore relatively short, e.g. the resident time at the plasma membrane of Drosophila imaginal disc cells is shorter than the time required for mCherry maturation, which is between 40 and 80  minutes (Couturier et  al. 2014). In uptake experiments with an antibody that binds the ECD of Notch, Notch localises in early endosomes (EEs) already after 5 min and is completely degraded after 5  h (Vaccari et  al. 2008; Windler and Bilder 2010). In mammalian


Fig. 3.2  Degradation of the Notch receptor by the endosomal pathway. Upon endocytosis, Notch is incorporated in early endosomal vesicles (EEVs). These EEVs undergo homotopic fusion to form an early endosome (EE) or fuse with already existing EEs. In the EE, Notch can return to the plasma membrane through a RME8-dependent pathway, which might include the passing through the recycling endosome (RE). However, the majority of Notch remains in the endosome, which matures and fuses with the lysosome where its content is degraded by the activity of acidic hydrolases. In the EE, the ICD of Notch is still in contact with the cytosol (red arrow). In order to get completely degraded, the ICD must be transferred into the lumen of the maturing endosome (ME). This is achieved by the action of the ESCRT machinery, whose central factor is Shrub/CHMP4. It mediates the abscission of Notch−/cargo-containing intraluminal vesicles (ILVs) into the lumen of the ME. As a result, the ME accumulates ILV and is recognisable as multi-vesicular bodies (MVBs) in the electron microscope (see insert). After incorporation of the cargo into ILVs, the ME fuses with the lysosome and the content is degraded

cells, pulse-chase experiments revealed that Notch1 appears in (not further specified) endosomes after 30 min and is degraded already after 60–90 min (Chastagner et al. 2008). Endocytosis of Notch is thought to be initiated by ubi of its ICD, performed by several E3 ligases, such as Deltex (Dx) and members of the

T. Reiff et al.

NEDD4 family, e.g. Suppressor of Deltex (Su(dx)) (Itch in mammals) and neural precursor cell-expressed, developmentally downregulated 4 (NEDD4) (reviewed in Schnute et al. (2018)). However, the requirement of ubi for endocytosis has not been rigorously tested. Indeed, it appears that Su(dx), as well as Dx, can elicit endocytosis of Notch in an ubi-independent manner, at least if over-expressed (Matsuno et  al. 2002; Shimizu et al. 2014). Hence, it is possible that they act as adapters physically linking Notch to the endocytosis core machinery, e.g. AP-2 and clathrin. Indeed, Dx is suggested to form a complex with the nonvisual ß-arrestin Kurz, which binds to AP-2 and clathrin in Drosophila (Mukherjee et al. 2005). As a result of endocytosis, Notch-containing early endosomal vesicles either fuse with each other to generate a new EE or fuse with already existing EEs (Fig. 3.2). In EE, Notch can return to the plasma membrane via a poorly characterised Rme8-/Rab4-dependent recycling pathway, but the majority is destined to be degraded in the lysosome. Therefore, Notch remains in the EE, which matures and eventually fuses with the lysosome where the luminal content of the matured endosome is degraded. In the EE, Notch is inserted in the limiting membrane (LM), meaning its ICD is still in contact with the cytosol (Fig.  3.2, red arrow). However, in order to get completely degraded, the ICD must be translocated into the lumen of the maturing endosome (ME). This is achieved by concentrating Notch (as well as other transmembrane cargo) at one spot of the LM, which is subsequently abscised into the lumen to form an intraluminal vesicle (ILV, Fig. 3.2). For the integration into ILVs, the cargo must be ubiquitylated. During maturation the endosome accumulates ILVs and is recognised as a multi-vesicular body (MVB) in the electron microscope (Fig. 3.2, insert). The abscission of ILVs is a complex process for which the eukaryotic cell uses a set of protein complexes collectively known as the endosomal sorting complex required for transport (ESCRT) machinery (Hurley 2015). The machinery consists of five in sequence acting complexes, termed ESCRT-0, ESCRT-I, ESCRT-II, ESCRT-III and

3  Unravelling of Hidden Secrets: The Tumour Suppressor Lethal (2) Giant Discs (Lgd)/CC2D1, Notch…

Vps4. ESCRT-0–II are stable complexes, which are recruited to the LM of the EE from the cytosol, whereas ESCRT-III assembles only on the LM from its monomeric cytosolic components. ESCRT-0–II recognise cargo via its ubiquitin label and concentrate it at a certain spot. ESCRT-II is also required to initiate the assembly of ESCRT-III, which is responsible for membrane abscission. For this purpose, it forms a polymer, consisting of Shrub or CHMP4  in Drosophila and mammals, respectively. The polymer is capped by Vps2/CHMP2 and Vps24/CHMP3. The polymerisation of Shrub/CHMP4 is initiated by Vps20/CHMP6. All four ESCRT-III core components are members of the CHMP family and share the same basic conformation. Shrub/ CHMP4 appears to assume two different conformations. In the cytosol, it exists in the closed conformation in which the negatively charged C-terminus folds back to contact the positively charged N-terminus that forms a helical bundle. At the LM it opens up to assume an extended helical hairpin conformation that allows polymerisation. The details of polymerisation are not understood, but Shrub in its open form has two complementary electrostatic surfaces that promote the association into a staggered array (McMillan et  al. 2016; Tang et  al. 2015) (Fig.  3.4d). The electrostatic surfaces are conserved among all Shrub orthologs in metazoans, suggesting that the mode of polymerisation is evolutionary conserved. Polymerisation of ESCRT-III is dynamic, and an assembled polymer is quickly disassembled by the AAA-ATPase complex Vps4. This disassembly is as crucial as assembly of ESCRT-III for the abscission to occur (Adell et al. 2017). After incorporation of Notch and other cargo into ILVs, the ME eventually fuses with the lysosome, and the luminal cargo is digested by the present activated acidic hydrolases (Fig. 3.2). As expected, the analysis of ESCRT-mutants in the electron microscope documented a severe distortion of the formation of ILVs and a dramatic enlargement of the MEs in ESCRT mutant cells (Stuffers et al. 2009). ESCRT-III together with Vps4 as a membrane abscission apparatus is used in many other processes where membrane is abscised away from the cytosol, such as membrane repair, cell divi-


sion and axon pruning. Moreover, it is hijacked by many enveloped viruses to exist in the infected cell, such as HIV and the Ebola virus (see Vietri et al. (2020)).

Lethal (2) Giant Discs (lgd) lgd is classified as a tumour suppressor gene in Drosophila, whose loss of function (lof) causes the formation of giant imaginal discs due to over-­ proliferation of the disc cells ((Bryant and Schubiger 1971, Buratovich and Bryant 1997), Fig.  3.3a, b’). lgd mutants die during the early pupal phase, probably due to the inability of the overgrown imaginal discs to correctly fuse with each other to form the body wall of the imago. Importantly, the epithelial organisation of the discs is not affected, indicating that lgd belongs to the class of hyperplasia causing tumour suppressor genes (hyperplastic class). Analysis of lgd mutant wing imaginal discs revealed that Notch target genes are ectopically activated in the wing primordia and that the over-proliferation is suppressed by loss of Notch signalling ((Klein 2003), Fig. 3.3a, b’). These findings indicate that the Notch pathway is either over-activated or ectopically activated in lgd mutants. Indeed, further analysis showed that the pathway is ectopically activated in all disc cells in a ligand-independent manner (Childress et  al. 2006; Gallagher and Knoblich 2006; Jaekel and Klein 2006). In addition, the ectopic activation in lgd mutant cells is independent on Kuzbanian (Kuz), the ADAM10 ortholog in flies performing the S2 cleavage, but dependent on the activity of the S3 performing γ-secretase (Jaekel and Klein 2006; Schneider et  al. 2012). Altogether, the results indicated that lgd lof causes uncontrolled ligand-independent activation of Notch in all imaginal disc cells in a cell autonomous manner. This holds true also for cells of the follicle epithelium of the ovary, suggesting that the activation of Notch is a general consequence of loss of lgd function in Drosophila (Morawa et al. 2015). Cells mutant for lgd contain enlarged Notch-­ positive MEs, indicating that Lgd is required during endosomal trafficking of Notch ((Schneider et al. 2012), Fig. 3.3d, d’). The ectopic activation


T. Reiff et al.

Fig. 3.3  The phenotype of lof of lgd in Drosophila. (a, a’) Expression of the endogenous target gene Wg (A) and the Notch activity reporter construct Gbe + Su(H) (a’) in wild-type wing imaginal discs. (b, b′) Expression of the marker in lgd mutant discs. The expression of the tissue-­ specific target Wg is dramatically expanded, while that of the more sensitive Gbe  +  Su(H) occurs in all disc cells, indicating ubiquitous activation of the Notch pathway in

the disc. (d, d’) Distribution of Notch in discs bearing lgd mutant cell clones (−/−). The clones are labelled by the absence of GFP; the distribution of Notch is revealed by antibody staining. The optical focus is within the cells and reveals that Notch is distributed in punctae in the cytosol. These punctae are MEs. The comparison shows that the mutant cells contain more and larger Notch-positive MEs

of Notch is suppressed in lgd mutants if the function of either hrs, which encodes a component of ESCRT-0, or of rab7, the organiser of fusion with the lysosome, is abolished (Schneider et al. 2012; Gallagher and Knoblich 2006). These findings indicate that the endosomal defect is the cause for the activation of the pathway in lgd mutants. The ultrastructural analysis revealed that the mutant cells contain all size classes of MEs of wild-type cells, but in addition also larger size classes (Schneider et  al. 2012). This phenotype can be explained by an increased lifetime of MEs in the mutant cells, which would allow more homotopic fusions between MEs to occur. In support of this interpretation is the finding that the

degradation of cargo, such as Notch, is also delayed in lgd cells, suggesting a longer lifetime of the MEs (Schneider et al. 2012). A genetic screen identified shrub as a locus that is in functional relationship with lgd (Troost et  al. 2012). Genetic interaction studies suggest that lgd is required for the full activity of shrub. In the absence of lgd function, the activity of shrub appears to be reduced, but not abolished. This assumption is based on the observation that lgd mutants die at an earlier time point if one copy of shrub is removed (genotype lgd +/lgd shrub), although shrub/+ flies are vital and display no pattern defects. Hence, the shift in the time point of death of the lgd +/lgd shrub flies

suggests that the activity of Shrub is lowered in lgd mutants to a degree that does not allow further reduction, e.g. brought about by removal of one copy of shrub. Altogether, the analysis established Lgd as a positive regulator of the activity of ESCRT-III. Similar to lgd, lof of shrub or other genes encoding elements of ESCRT-I, ESCRT-ll and ESCRT-III cause ectopic ligand-independent activation of the Notch pathway (Thompson et al. 2005; Vaccari and Bilder 2005; Vaccari et  al. 2009). However, lof of ESCRT additionally prolongs signalling via other pathways, such as the BMP/Dpp and Wg/Wnt pathways (Thompson et al. 2005). A similar prolongation of signalling via the BMP/Dpp pathway has been observed upon lof of lgd only in the germline and the follicle epithelium of the ovary (Morawa et  al. 2015). The prolonged signalling causes the formation of supernumerary stem cells and the induction of one additional round of cell division of the cyst cells. The lgd mutant phenotype resembles that observed in the ovary of shrub heterozygous flies, indicating that also in this case Lgd is functionally connected to Shrub (Morawa et al. 2015). A further consequence of the loss of ESCRT function is the loss of epithelial polarity that in combination with the cell over-proliferation leads to the formation of a large multilayer of undifferentiated cells (neoplastic phenotype), instead of a well-patterned epithelial monolayer (Vaccari et  al. 2009). These additional phenotypes of ESCRT mutants are not observed in lgd mutants, although Lgd is a positive regulator of Shrub. The discrepancy in the phenotypes is not understood. A possible explanation is that the reduction, but not complete loss of shrub activity, caused by the loss of lgd function only causes a hyperplastic phenotype, while the complete lof of shrub causes the more drastic neoplastic phenotype.

The Molecular Function of Lgd lgd encodes a protein of 816 amino acids that contains 4 repeats of the DM14 domain, followed by a linker region and a C2 domain ((Childress

et al. 2006; Gallagher and Knoblich 2006; Jaekel and Klein 2006), Fig. 3.4a). Orthologs exist in all metazoans with similar domain organisation. Mammals have two variants in their genomes, termed LGD1 and LGD2. LGD1 and LGD2 have alternative names, which partly reflect the different functions found in experiments: LGD1 is also called coiled-coil and C2 domain-containing protein 1B (CC2D1B) and FRE-binding protein, five repressor element under dual repression-binding protein-2 (FREUD-2), whereas LGD2 is also termed CC2D1A, Akt kinase-interacting protein 1 (Aki1), TBK-associated protein in endolysosomes (TAPE) and FREUD-1 (Matsuda et  al. 2003; Ou et al. 2003; Hadjighassem et al. 2009; Nakamura et  al. 2008; Chang et  al. 2011). For reasons of simplicity, we will use a double name Lgd/CC2D1 in the following. The unique hallmark of the Lgd family is the helical hairpin forming DM14 domain ((Childress et al. 2006, Gallagher and Knoblich 2006, Jaekel and Klein 2006, McMillan et  al. 2017) Fig. 3.4c). All family members of metazoans have four tandem repeats of this domain. Pull-down experiments indicated that the DM14 domain-containing region is required for the direct physical interaction with Shrub, revealing a molecular basis for the functional relationship of both genes found in the genetic analysis (McMillan et  al. 2017). Sequence comparison of the four DM14 domains revealed that, in each ortholog, the odd-numbered domains (DM14–1 and DM14–3) are more similar to each other than to the even-numbered ones (DM14–2 and DM14–4). Likewise, the even-­ numbered domains are more related to each other than to the odd-numbered ones. The odd-­ numbered DM14 domains have an extended positively charged surface (KARR motif) that is absent in the even-numbered domains (Fig.  3.3b). Lgd binds directly to the negative electrostatic surface of Shrub via the positive surface of the oddnumbered domains (Fig.3.3d (McMillan et  al. 2017)). The negative surface of Shrub is also required for its homo-polymerisation at the LM of the ME, suggesting that binding of Lgd to Shrub and polymerisation of Shrub are mutually exclusive events (Fig. 3.4d).


Fig. 3.4  The molecular characterisation of Lgd/CC2d1 proteins. (a) Domain architecture of Lgd/CC2D1a. It consists of four repeats of the DM14 domain followed by a linker region that connects the DM14 domains with a C2 domain at the C-terminus. (b) Sequence comparisons of the DM14 domains of Lgd with the orthologs of mouse and human. It reveals that the odd-numbered domains contain an extended positive surface (KARR motif). (c)

T. Reiff et al.

Atomic structure of the third DM14 domain of Lgd. It is a helical hairpin with a positive charged surface patch created by the KARR motif (blue). (d) The positive patch binds to the negative surface of Shrub. This surface is also required for the polymerisation of Shrub. Hence, Lgd binding to Shrub and Shrub polymerisation are mutually exclusive

3  Unravelling of Hidden Secrets: The Tumour Suppressor Lethal (2) Giant Discs (Lgd)/CC2D1, Notch…

Strangely, although the even-numbered DM14 domains are present in all orthologs, they appear to be dispensable for function in Drosophila, indicated by the finding that Lgd variants with only one odd-numbered domain (e.g. DM14–3) can fully rescue lgd mutants, while variants with only even-numbered ones (e.g. DM14–4) failed to do so (McMillan et al. 2017). In further support of this conclusion, DM14–4 does not bind to Shrub in vitro (McMillan et al. 2017). The loss of its C2 domain results in a mis-localisation of Lgd into the nucleus and a loss of its activity. Hence, the C2 domain is required for the correct subcellular localisation of Lgd in the cytosol. Additionally, it contributes to the stability of Lgd (Troost et al. 2012). Experiments with tagged versions and anti-­Lgd antibody staining revealed that Lgd is diffusely distributed in the cytosol (Childress et  al. 2006, Gallagher and Knoblich 2006, Jaekel and Klein 2006). Combined with the fact that Lgd binding to Shrub and Shrub polymerisation is mutually exclusive, this finding suggests that Lgd binds to the monomeric cytosolic closed form of Shrub. It is assumed that adopting the closed conformation is essential to prevent inappropriate polymerisation in the cytosol. Thus, a possible way how Lgd might act is that by binding it helps Shrub to adopt or stay in the closed conformation.

 ctivation of Notch During A Endosomal Trafficking in lgd Mutants Lof of shrub or lgd results in activation of Notch during endosome maturation. The major task of Shrub in this process is the formation of ILVs and in its absence this process is impaired. A consequence of the failure of ILV formation is that Notch and other cargo remains in the LM of the ME.  The ICD of Notch in the LM protrudes in the cytosol, even after fusion with the lysosome. Somehow the ICD of Notch must be released from the LM of the lysosome. A realistic scenario how this occurs is that the active acidic hydrolases of the lysosomal lumen degrade the ECD of Notch, thereby creating a NEXT-like variant


inserted in the LM that is cleaved by γ-secretase. γ-Secretase at the lysosome is very abundant and active (Pasternak et al. 2003). Alternatively, or in addition, the acidic environment and the occurring export of ions, especially Ca2+, from the lumen of the ME, might be sufficient to severe the salt bridge in the HD of Notch and thereby achieve the shedding of the ecto-domain of Notch (reviewed in Scott and Gruenberg (2010)). In any case, the result is an alternative ecto-domain shedding of Notch as it also occurs during ligand-­ dependent activation. A similar model has been suggested also for the activation of Notch in lgd mutants, but a few differences have to be taken into account (Fig. 3.5). If shrub activity is reduced in lgd mutants, one possible effect would be a failure of ILV formation. However, lgd mutant cells still contain MVBs, indicating that ILV formation still occurs (Schneider et al. 2012). Thus, in principle Notch can be incorporated into ILVs and thereby removed from the LM in Lgd cells. It is possible that the rate of ILV formation is reduced, thereby allowing a fraction of Notch to remain on the LM.  However, it has not been determined so far, whether lgd mutant MVBs contain fewer ILVs. Nevertheless, elegant recent work by the Schweisguth lab suggests that indeed a fraction of Notch escapes the incorporation into ILVs in lgd mutants (Couturier et al. 2014). It is this fraction which is thought to be activated as described upon fusion of the ME with the lysosome (Fig. 3.5 (Schneider et al. 2012)). Further results provide support for the suggested model of Notch activation in lgd mutant cells: the activation (1) depends on the fusion of the ME with the lysosome and (2) requires the activity of the V-ATPase that acidifies the lumen of the ME (Schneider et  al. 2012; Troost et  al. 2012). The acidification is required for the acidic lysosomal hydrolases to be activated. Although the proposed model of activation is plausible, it is not proven. For example, it has not been shown whether Notch that remains at the LM of the lysosome is really activated in a ligand-independent manner. It is noteworthy to mention here that the endosomal activation of Notch is required for proper development in Drosophila. It has been shown


T. Reiff et al.

Fig. 3.5  Model of activation of Notch in lgd mutant cells. In lgd mutant cells, Notch is normally endocytosed and transported to the EE.  However, due to the reduction of the activity of Shrub, a fraction of Notch escapes the incorporation into ILVs. Upon fusion with the lysosome, the ECD of this fraction is removed by the activity of the acidic hydrolases. Alternatively, or in concert, the acidic environment of the lysosomal lumen and the lack of Ca2+

induce the separation of the ECD from the remainder of Notch. In any case, the result of this ligand-independent ecto-domain shedding is a NEXT-like intermediate that is cleaved by γ-secretase to release NICD into the cytosol. NICD travels to the nucleus where it activates the expression of the target genes in an activator complex with CSL and co-factors

that an additional function of Su(dx) and Dx is to regulate the amount of Notch incorporated into ILVs. The Su(dx)/Dx mechanism assures a basal activity of Notch signalling required for development (Shimizu et al. 2014; Wilkin et al. 2008).

behavioural deficits that are cognitive and social impairment, anxiety, hyperactivity and repetitive behaviours (Oaks et  al. 2017). Interestingly, lof of LGD2/CC2D1A in humans is not lethal after birth, but causes mental retardation and autism spectrum disorder (Basel-Vanagaite et  al. 2006; Manzini et  al. 2014). A likely cause of these pathologic traits is a reduction in dendritic complexity observed in ex  vivo culture assays (Manzini et al. 2014). In contrast, lof of Lgd1/CC2D1B has no obvious consequences for development or life span, and homozygous mutant mice can be maintained as a strain (Drusenheimer et al. 2015). The lack of phenotype of Lgd1 mutants can be a result of an extensive functional identity/compensation/ redundancy among both LGDs in mammals.

Function of Lgd in Mammals So far, the information about the function of Lgd in mammals is confusing and points to a variety of functions. Lof of Lgd2/CC2D1a in mice results in postnatal death due to a brain defect that causes a failure in breathing (Al-Tawashi et al. 2012; Drusenheimer et al. 2015; Chen et al. 2012; Zhao et al. 2010). The conditional KO of Lgd2/Cc2D1a in the forebrain causes a variety of

3  Unravelling of Hidden Secrets: The Tumour Suppressor Lethal (2) Giant Discs (Lgd)/CC2D1, Notch…

Indeed, this appears to be the case: both genes are similarly expressed in all tissues of mouse tested (Drusenheimer et  al. 2015). Moreover, Lgd1 Lgd2 double mutant mice die early in development, before E11.5 (Zamarbide et  al. 2018). Since single mutants either die after birth with no gross defects (Lgd2/CC2D1a) or are viable (Lgd1/CC2D1b), this synergistic phenotype indicates an extensive functional redundancy among the Lgd/CC2D1 paralogs. Unfortunately, neither the double mutant embryos nor double mutant MEFs have been analysed so far. Although the two Lgd paralogs share a functional redundancy, they also differ in some aspects, which is already indicated by the difference in lethality. The difference is also manifested in other phenotypic aspects: lof of LGD2/CC2D1A in the forebrain causes an array of cognitive and social defects, anxiety and hyperactivity, while the lof of LGD1/CC2D1B leads only to cognitive deficits (Zamarbide et al. 2018). Several experiments revealed that the molecular relationship between Lgd and Shrub is conserved in mammals as well. Rescue experiments in Drosophila showed that LGD1/CC2D1B and LGD2/CC2D1A can rescue lgd mutant flies, albeit to different degree (Drusenheimer et  al. 2015). While LGD1, which is more similar in sequence to Lgd than LGD2, rescues completely, the recue by LGD2 is only partial, even if present in two copies in the genome. The rescue of lgd mutants by the mammalian orthologs is further proof that both mammalian paralogs have an at least partially redundant molecular function, which is shared by Lgd of Drosophila. The rescue activity of LGD2 in flies is dependent on the function of shrub, suggesting that also the functional relationship with Shrub is conserved (Drusenheimer et al. 2015). In agreement, it has been shown that both mammalian Lgd orthologs bind to the three Shrub orthologs in mammals CHMP4B, CHMP4A and, weaker, CHMP4C (Drusenheimer et  al. 2015; Usami et  al. 2012; Tsang et  al. 2006). The binding to CHMP4B appears to be mediated largely via DM14–3. Hence, the intimate relationship between Lgd and Shrub appears to be conserved in evolution.


Similar to Drosophila, in vitro and in vivo studies also point to a role of Lgd1 and Lgd2 in the regulation of the function of the ESCRT machinery in mammals. LGD2/CC2D1a has been found as an endosomal protein in a multiparametric survey of endocytosis, as a factor that negatively affects endosomal trafficking in cell culture cells (Collinet et al. 2010). We found that (1) the deficiency of Lgd2 results in an enlargement of MEs, (2) Lgd2 and Chmp4b interact with each other in living cells and (3) both Lgds cycle together with CHMP4B between the cytosol and the LM of the ME (Drusenheimer et al. 2015). It appears that the LGDs are also required for the regulation of several signalling pathways in mammals, ranging from Toll, over the EGFR, to the nuclear factor kB, to PDK1/Akt, to cAMP/ PKA, to bone morphogenetic protein and PKA signalling (Zhao et al. 2010; Rogaeva et al. 2007; Ou et al. 2003; Hadjighassem et al. 2009; Chen et al. 2012; Chang et al. 2011). At least in the case of TLR and EGFR signalling, the effects are linked to a defect in ESCRT function or at least to a malfunction of endosomes (Chang et al. 2011; Deshar et al. 2016). Whether a malfunction of the endosomal pathway is causative also for the effects on the activity of the other pathways remains to be determined. Besides the conserved function in endocytosis, LGDs in mammals appear to have additional functions so far not identified in Drosophila and independent of endosome trafficking. It has recently been shown that LGD1/CC2D1B is required for the correct timing of nuclear envelope closure after cell division in concert with the Shrub ortholog CHMP4B (Ventimiglia et  al. 2018). Lof of LGD1/CC2D1B results in defective envelope reformation and therefore causes an aberrant envelope morphology. Interestingly, this defect appears not to severely impact on vitality of LGD1/CC2D1B mutant mice. As mentioned above, mutant mice are healthy and fertile. A possible explanation for this puzzle is the incomplete penetrance of the envelope phenotype. It is not known whether also LGD2/CC2D1A is involved in envelope reformation and is responsible for this lack of penetrance.


The study by Ventimiglia et  al. (2018) also revealed a second important aspect: they found that LGD1/CC2D1B interacts also with another CHMP family member, CHMP7, during envelope closure. In this case the fourth DM14 domain mediates the direct interaction between the proteins (Ventimiglia et  al. 2018). Moreover, they found that Lgd2/CC2D1B can interact with CHMP2A.  Hence, the LGDs can interact with several members of the CHMP family. The significance of these interactions might have been overlooked so far, since, like LGD, CHMP2A and CHMP7 regulate the activity of CHMP4B. Hence, the consequence of their inactivation is always the lof of CHMP4B. Interestingly, LGD2/CC2D1a appears not to interact with CHMP2A (Usami et al. 2012). Thus, there might be also differences among the LGDs in the capacity of binding CHMP family members. For the more studied LGD2/CC2D1a, a variety of additional functions have been found which appear not to be associated with its endosomal function. It has been reported to regulate centrosome cohesion, and loss of its function causes formation of multipolar spindles during cell division and multinucleated cells in HeLa cell cultures (Nakamura et  al. 2009). However, the phenotypes were not observed in MEFs obtained from Lgd2 mutant mice, suggesting that either a functional difference of Lgd2 between mice and humans or a differential requirement in diverse cell types exists (Drusenheimer et  al. 2015). In another function, LGD2/CC2D1A appears to act as a scaffold protein that assembles complexes important in cAMP/PKA and PDK1/ AKT signalling (Al-Tawashi et  al. 2012; Nakamura et al. 2008). In the case of the PDK1/ Akt1 module, LGD2/CC2D1a (here termed Aki/ FREUD1) links the module specifically to the EGFR.  Interestingly, also the interaction of LGD2 with PDK1 appears to be mediated by the fourth DM14 domain. The involvement in EGFR/ Akt signalling raises the possibility that Lgd2/ CC2D1A might be involved in cancer in a Notch-­ independent way in humans. Indeed, recent work suggests that it might be a potential therapeutic target in lung, ovarian and pancreatic cancer (Ohtsubo et al. 2014; Yamada et al. 2013; Kumar et al. 2019).

T. Reiff et al.

The most surprising function of LGD1/CC2D1A and LGD2/CC2D1B is the one as a transcriptional repressor that represses the expression of serotonin-1A auto-receptors. This finding provides a molecular link of both genes to depression and anxiety (Ou et al. 2003; Rogaeva et  al. 2007; Hadjighassem et  al. 2009; Vahid-­ Ansari et al. 2017). The DNA-binding activity of LGD2/CC2D1a has not been determined, but the linker region that connects DM14–4 with the C2 domain was predicted to fold in a HLH conformation typical for bHLH transcription factors (Ou et al. 2003). However, Freud-1 lacks a clear nuclear localisation sequence, and a sequence comparison between LGD2/CC2D1a (Freud-1) and several Lgd family members revealed that the putative HLH region is poorly conserved. Moreover, although not similar in sequence, the respective region in Drosophila Lgd adopts a similar helical hairpin conformation as the DM14 domains (Ventimiglia et  al. 2018). Thus, it remains to be determined whether the proposed region has DNA-binding properties in all Lgds or is an additional DM14 domain.

I s Notch Activated in Mammals Upon Loss of LGD or ESCRT Function? In Drosophila lof of lgd causes the uncontrolled ligand-independent activation of the Notch pathway due to a reduction of the endosomal function of the ESCRT machinery. This raises the obvious question whether the lof of LGD/CC2D1a or ESCRT function causes a similar activation of the Notch pathway. Uncontrolled activation of Notch has been observed as a cause of various cancers, among them T-cell leukaemia, such as T-ALL (Aster et al. 2017). In T-ALL the NRR of Notch1 is affected by mutations that results in a release of autoinhibition and activation of the receptor in a ligand-independent manner. However, this activation requires no defect in endosomal trafficking. It has been recently shown that Notch3 is activated apparently in a ligand-­ independent manner in breast cancer cells. Although this mechanism is not entirely understood, some results suggest that the activation

3  Unravelling of Hidden Secrets: The Tumour Suppressor Lethal (2) Giant Discs (Lgd)/CC2D1, Notch…

occurs at the plasma membrane (Choy et  al. 2017). Whereas in these cases the endosomal involvement in ligand-independent Notch activation is not obvious, it appears to be a requirement for the ligand-independent activation of Notch in the immunological synapse (Steinbuck et  al. 2018). Here, the activation of the T-cell receptor in combination with CD8 causes endocytosis of Notch and the activation of ADAM10 and ADAM17, which perform the S2 cleavage of Notch in the LM of the ME.  Apparently, the luminal environment of the ME releases Notch from autoinhibition, allowing the S2 cleavage by the ADAMs. While in this case Notch is activated in the ME, it differs from ligand-independent activation in ESCRT or lgd mutant cells through the requirement of the S2 cleavage, by the ADAMs. Altogether, these recent reports document that uncontrolled ligand-independent activation of the Notch pathway occurs also in mammals, even during endosomal trafficking, but evidence for its activation upon lof of lgd or ESCRT is scarce so far. Loss of ESCRT function in mouse causes lethality during early embryogenesis at a similar stage as in Lgd1 Lgd2 double mutants (Wagner et  al. 2003; Lee et  al. 2007). In most cases the activity of Notch has not been monitored. In case of CHMP5 lof, at least several pathways are activated, among them TGFß/BMP, RTK pathways that activate the ERK1/2 module, NFκB and also the TLR4 pathway (Shim et al. 2006). CHMP5, Vps60 in yeast, is a so-called accessory ESCRT protein, which is nonessential in yeast. It is required for full ESCRT-III/Vps4 function. In Drosophila, its lof causes a cold-sensitive phenotype that includes weak ectopic activation of the Notch pathway (Bäumers et  al. 2019). Unfortunately, Notch signalling appears not to be tested in mouse CHMP5 mutants. The mammalian intestinal epithelium is a rapidly renewing tissue where the differentiated cells are replaced within 2–5 days. Functionally distinct epithelial cells are constantly generated by resident stem cells in the crypt of each villus.


Thus, matching intestinal stem cell (ISC) production and their timely differentiation has to be tightly controlled and accurate. Homeostasis is maintained by actively cycling ISC, so-called CBCs (crypt base columnar cells) expressing the Wnt pathway component Lgr5 (leucine-rich repeat-containing G-protein-coupled receptor 5) with basal location in the crypt (Barker et  al. 2007). Self-renewal of CBCs is controlled through gradients of wingless-related integration site (WNT), Hedgehog (HH), bone morphogenetic protein (BMP) and Notch signalling pathways (Geissler and Zach 2012; Takebe et  al. 2011). The lof of the Notch pathway results in the loss of the stem cells, while its ectopic activation causes a dramatic expansion of the stem cell compartment, indicating that it is an essential signal in the stem cell niche (). The pathway has a second function during differentiation of the precursor cells. When blocked, the stem and precursor cells differentiate into the secretory lineage causing a hyperplasia of mucus-secreting Goblet cells (GCs), while activation of the Notch pathways inhibits GC differentiation. Therefore, the density of GCs in the epithelium is a measure of Notch activity. This assay was used to test whether the KO of LGD1 or LGD2 in the gut epithelium causes changes in Goblet cell density. However, this was not the case, indicating that individual KO of either LGD ortholog does not significantly affect Notch signalling in the gut epithelium (Drusenheimer et  al. 2015). Nevertheless, due to the extensive functional redundancy among the two Lgds, the final verdict is still out, as long as the double KO in gut cells is not analysed. Acknowledgements  Work in the Klein lab is supported by the Deutsche Forschungsgemeinschaft (DFG) through Teilprojekt B01 of the CRC 1208 “Identity and Dynamics of Membrane Systems-from Molecules to Cellular Functions” and Sachbeihilfe KL-1028/5-2. We apologise to every researcher whose publications are not cited due to restrictions in space. The Reiff lab is supported by the Deutsche Forschungsgemeinschaft (DFG) by Sachbeihilfe RE-3453/3-1 and the Wilhelm Sander-Stiftung 2018.145.1.


References Adell M, Migliano SM, Upadhyayula S, Bykov YS, Sprenger S, Pakdel M, Vogel GF, Jih G, Skillern W, Behrouzi R, Babst M, Schmidt O, Hess MW, Briggs JA, Kirchhausen T, Teis D (2017) Recruitment dynamics of ESCRT-III and Vps4 to endosomes and implications for reverse membrane budding. eLife. 2017; 6:e31652 Al-Tawashi A, Jung SY, Liu D, Su B, Qin J (2012) Protein implicated in nonsyndromic mental retardation regulates protein kinase A (PKA) activity. J Biol Chem 287:14544–14558 Arnett KL, Seegar TCM, Blacklow SC (2018) Structural biology of Notch signaling. In: Miele L, ArtavanisTsakonas S (eds) Targeting Notch in cancer. Springer Science+Business Media, LLC, part of Springer Nature 2018 Aster JC, Pear WS, Blacklow SC (2017) The varied roles of Notch in cancer. Annu Rev Pathol Mech Dis 12:245–275 Barker N, van Es JH, Kuipers J, Kujala P, van den Born M, Cozijnsen M, Haegebarth A, Korving J, Begthel H, Peters PJ, Clevers H (2007) Identification of stem cells in small intestine and colon by marker gene Lgr5. Nature 449:1003–1007 Basel-Vanagaite L, Attia R, Yahav M, Ferland RJ, Anteki L, Walsh CA, Olender T, Straussberg R, Magal N, Taub E, Drasinover V, Alkelai A, Bercovich D, Rechavi G, Simon AJ, Shohat M (2006) The CC2D1A, a member of a new gene family with C2 domains, is involved in autosomal recessive non-syndromic mental retardation. J Med Genet 43:203–210 Bäumers M, Klose S, Brüser C, Haag C, Hänsch S, Pannen H, Weidtkamp-Peters S, Feldbrügge M, Klein T (2019) The auxiliary ESCRT complexes provide robustness to cold in poikilothermic organisms. Biology Open 2019 8:bio043422 Berndt N, Seib E, Kim S, Troost T, Lyga M, Langenbach J, Haensch S, Kalodimou K, Delidakis C, Klein T (2017) Ubiquitylation-independent activation of Notch signalling by Delta. Elife. 2017 Sep 29;6:e27346 Bryant PJ, Schubiger G (1971) Giant and duplicated imaginal discs in a new lethal mutant of Drosophila melanogaster. Dev Biol 24:233–263 Buratovich MA, Bryant PJ (1997) Enhancement of overgrowth by gene interactions in lethal(2)giant discs imaginal discs from Drosophila melanogaster. Genetics 147:657–670 Chang C-H, Lai L-C, Cheng H-C, Chen K-R, Syue Y-Z, Lu H-C, Lin W-Y, Chen S-H, Huang H-S, Shiau A-L, Lei H-Y, Qin J, Ling P (2011) TBK1-associated Protein in Endolysosomes (TAPE) is an innate immune regulator modulating the TLR3 and TLR4 signaling pathways. JBC 286:7043–7051 Chastagner P, Israel A, Brou C (2008) AIP4/Itch regulates Notch receptor degradation in the absence of ligand. PLoS ONE 3(7):e2735

T. Reiff et al. Chastagner P, Rubinstein E, Brou C (2017) Ligand-­ activated Notch undergoes DTX4-mediated ubiquitylation and bilateral endocytosis before ADAM10 processing. Sci Signal 10:1–13 Chen KR, Chang CH, Huang CY, Lin CY, Lin WY, Lo YC, Yang CY, Hsing EW, Chen LF, Shih SR, Shiau AL, Lei HY, Tan TH, Ling P (2012) TBK1-associated protein in endolysosomes (TAPE)/CC2D1A is a key regulator linking RIG-I-like receptors to antiviral immunity. J Biol Chem 287:32216–32221 Childress JL, Acar M, Tao C, Halder G (2006) Lethal Giant discs, a novel C2-domain protein, restricts Notch activation during endocytosis. Curr Biol 16:1–6 Choy L, Hagenbeek TJ, Solon M, French D, Finkle D, Shelton A, Venook R, Brauer MJ, Siebel CW (2017) Constitutive NOTCH3 signaling promotes the growth of basal breast cancers. Cancer Res 77:1439–1452 Collinet C, Stoöter M, Bradshaw CR, Samusik N, Rink JC, Kenski D, Habermann B, Buchholz F, Henschel R, Mueller MS, Nagel WE, Fava E, Kalaidzidis Y, Zerial M (2010) Systems survey of endocytosis by multiparametric image analysis. Nature 464:243–250 Couturier L, Trylinski M, Mazouni K, Darnet L, Schweisguth F (2014) A fluorescent tagging approach in Drosophila reveals late endosomal trafficking of Notch and Sanpodo. J Cell Biol 207:351–363 Daskalaki A, Shalaby NA, Kux K, Tsoumpekos G, Tsibidis GD, Muskavitch MA, Delidakis C (2011) Distinct intracellular motifs of Delta mediate its ubiquitylation and activation by Mindbomb1 and Neuralized. J Cell Biol 195:1017–1031 Deshar R, Cho EB, Yoon SK, Yoon JB (2016) CC2D1A and CC2D1B regulate degradation and signaling of EGFR and TLR4. Biochem Biophys Res Commun 480:280–287 Drusenheimer N, Migdal B, Jäckel S, Tveriakhina L, Scheider K, Schulz K, Gröper J, Köhrer K, Klein T (2015) The mammalian Orthologs of Drosophila Lgd, CC2D1A and CC2D1B, function in the endocytic pathway, but their individual loss of function does not affect Notch signalling. PLoS Genet 11 (12):e1005749 Fontana JR, Posakony JW (2009) Both inhibition and activation of notch signaling rely on a conserved neuralized-­binding motif in bearded proteins and the Notch ligand delta. Dev Biol 333:373–385 Gallagher CM, Knoblich J (2006) The conserved c2 domain protein lethal (2) giant discs regulates protein trafficking in Drosophila. Dev Cell 11:641–653 Geissler K, Zach O (2012) Pathways involved in Drosophila and human cancer development: the Notch, Hedgehog, Wingless, Runt, and Trithorax pathway. Ann Hematol 91:645–669 Hadjighassem MR, Austin MC, Szewcyk B, Daigle M, Stockmeier CA, Albert PR (2009) Human Freud-2/ CC2D1B: a novel repressor of postsynaptic serotonin­1A receptor expression. Biol Psychiatry 66:214–222 Huotari J, Helenius A (2011) Endosome maturation. EMBO J 30:3481–3500

3  Unravelling of Hidden Secrets: The Tumour Suppressor Lethal (2) Giant Discs (Lgd)/CC2D1, Notch… Hurley JH (2015) ESCRTs are everywhere. EMBO J 34:2398–2407 Jaekel R, Klein T (2006) The Drosophila Notch inhibitor and tumor suppressor gene lethal (2) giant discs encodes a conserved regulator of endosomal trafficking. Dev Cell 11:655–669 Jekely G, Rorth P (2003) Hrs mediates downregulation of multiple signalling receptors in Drosophila. EMBO Rep 4:1164–1168 Klein T (2003) The tumour suppressor gene l(2)giant discs is required to restrict the activity of Notch to the dorsoventral boundary during Drosophila wing development. Dev Biol 255:313–333 Kovall RA, Gebelein B, Sprinzak D, Kopan R (2017) The canonical Notch signalling pathway: structural and biochemical insights into shape, sugar, and force. Dev Cell 41:228–241 Kumar S, Oien DB, Khurana A, Cliby W, Hartmann L, Chien J, Shridhar V (2019) Coiled-coil and C2 Domain-Containing Protein 1A (CC2D1A) promotes chemotherapy resistance in ovarian cancer. Front Oncol 9:986 Lee JA, Beigneux A, Ahmad ST, Young SG, Gao F-B (2007) ESCRT-III dysfunction causes autophagosome accumulation and neurodegeneration. Curr Biol 17:1561–1567 Manzini MC, Xiong L, Shaheen R, Tambunan DE, Di Costanzo S, Mitisalis V, Tischfield DJ, Cinquino A, Ghaziuddin M, Christian M, Jiang Q, Laurent S, Nanjiani ZA, Rasheed S, Hill RS, Lizarraga SB, Gleason D, Sabbagh D, Salih MA, Alkuraya FS, Walsh CA (2014) CC2D1A regulates human intellectual and social function as well as NF-κB signaling homeostasis. Cell Rep 8:647–655 Matsuda A, Suzuki Y, Honda G, Muramatsu S, Matsuzaki O, Nagano Y, Doi T, Shimotohno K, Harada T, Nishida E, Hayashi H, Sugano S (2003) Large-scale identification and characterization of human genes that activate NF-kappaB and MAPK signaling pathways. Oncogene 22:3307–3318 Matsuno K, Ito M, Hori K, Miyashita F, Suzuki S, Kishi N, Artavanis-Tsakonas S, Okano H (2002) Involvement of a proline-rich motif and RING-H2 finger of Deltex in the regulation of Notch-signaling. Development 129:1049–1159 McMillan BJ, Schnute B, Ohlenhard N, Zimmerman B, Miles L, Beglova N, Klein T, Blacklow SC (2015) A tail of two sites: structural basis for recognition of Notch ligands by Mind bomb E3 ligases. Mol Cell 57:912–924 McMillan BJ, Tibbe C, Jeon H, Drabek AA, Klein T, Blacklow SC (2016) Electrostatic interactions between elongated monomers drive Filamentation of Drosophila shrub, a metazoan ESCRT-III protein. Cell Rep 16:1211–1217 McMillan BJ, Tibbe C, Drabek AA, Seegar TCM, Blacklow SC, Klein T (2017) Structural basis for regulation of ESCRT-III complexes by Lgd. Cell Rep 19:1–8


Morawa K, Schneider M, Klein T (2015) Lgd regulates the activity of the BMP/Dpp signalling pathway during Drosophila oogenesis. Development 142:1325–1335 Mukherjee A, Veraksa A, Bauer A, Rosse C, Camonis J, Artavanis-Tsakonas S (2005) Regulation of Notch signalling by non-visual ß-arrestin. Nat Cell Biol 7:1191–1201 Nakamura A, Naito M, Tsuruo T, Fujita N (2008) Freud-1/ Aki1, a novel PDK1-interacting protein, functions as a scaffold to activate the PDK1/Akt pathway in epidermal growth factor signaling. MCB 28:5996–6009 Nakamura A, Arai H, Fujita M (2009) Centrosomal Aki1 and cohesin function in separase-regulated centriole disengagement. JCB 187:607–614 Oaks AW, Zamarbide M, Tambunan DE, Santini E, Di Costanzo S, Pond HL, Johnson MW, Lin J, Gonzalez DM, Boehler JF, Wu GK, Klann E, Walsh CA, Manzini MC (2017) Cc2d1a loss of function disrupts functional and morphological development in forebrain neurons leading to cognitive and social deficits. Cereb Cortex 27:1670–1685 Ohtsubo K, Yamada T, Zhao L, Jin TF, Takeuchi S, Mouri H, Yamashita K, Yasumoto K, Fujita N, Kitagawa H, Ohta T, Ikeda H, Yano S (2014) Expression of Akt kinase-interacting protein 1, a scaffold protein of the PI3K/PDK1/Akt pathway, in pancreatic cancer. Pancreas 43:1093–1100 Ou X-M, Lemonde S, Jafar-Nejad H, Bown CD, Goto A, Rogaeva A, Albert PR (2003) Freud-1: a neuronal calcium-regulated repressor of the 5-HT1A receptor gene. J Neurosci 23:7415–7425 Pasternak SH, Bagshaw RD, Guiral M, Zhang S, Ackerley CA, Pak BJ, Callahan JW, Mahuran DJ (2003) Presenilin-1, nicastrin, amyloid precursor protein, and gamma-secretase activity are co-localized in the lysosomal membrane. J Biol Chem (29):26687–26694 Rogaeva A, Ou XM, Jafar-Nejad H, Lemonde S, Albert PR (2007) Differential repression by freud-1/CC2D1A at a polymorphic site in the dopamine-D2 receptor gene. J Biol Chem 282:20897–20905 Schneider M, Troost T, Grawe F, Martinez-Arias A, Klein T (2012) Activation of Notch in lgd mutant cells requires the fusion of late endosomes with the lysosome. J Cell Sci 126:645–656 Schnute B, Troost T, Klein T (2018) Endocytic trafficking of the Notch receptor. Adv Exp Med Biol 1066:99–122 Scott CC, Gruenberg J (2010) Ion flux and the function of endosomes and lysosomes: pH is just the start. Bioassays 33:103–110 Shim J-H, Cxiao C, Hayden MS, Lee K-Y, Trombetta ES, Pypaert M, Nara A, Yoshimori T, Wilm B, Erdjument-­ Bromage H, Tempst P, Hogan BLM, Mellman I, Gosh S (2006) CHMP5 is essential for late endosome function and down-regulation of receptor signaling during mouse embryogenesis. JCB 172:1045–1056 Shimizu H, Woodcock SA, Wilkin MB, Trubenová B, Monk NA, Baron M (2014) Compensatory flux changes within an endocytic trafficking network maintain thermal robustness of Notch signaling. Cell (5):1160–1174

46 Siebel C, Lendahl U (2017) Notch signaling in development, tissue homeostasis, and disease. Physiol Rev 97:1235–1294 Steinbuck MP, Arakcheeva K, Winandy S (2018) Novel TCR-mediated mechanisms of Notch activation and signaling. J Immunol 200:997–1007 Struhl G, Adachi A (2000) Requirements for Presenilin-­ dependent cleavage of Notch and other transmembrane proteins. Mol Cell 6:625–636 Stuffers S, Wegner CS, Stenmark H, Brech A (2009) Multivesicular endosome biogenesis in the absence of ESCRTs. Traffic 10:925–937 Takebe N, Harris PJ, Warren RQ, Ivy SP (2011) Targeting cancer stem cells by inhibiting Wnt, Notch, and Hedgehog pathways. Nat Rev Clin Oncol 8:97–106 Tang S, Henne WM, Borbat PP, Buchkovich NJ, Freed JH, Mao Y, Fromme JC, EMR SD (2015) Structural basis for activation, assembly and membrane binding of ESCRT-III Snf7 filaments. elife 4 Thompson BJ, Mathieu J, Sung HH, Loeser E, Rorth P, Cohen SM (2005) Tumor suppressor properties of the ESCRT-II complex component Vps25 in Drosophila. Dev Cell 9:711–720 Troost T, Jaeckel S, Ohlenhard N, Klein T (2012) The tumour suppressor Lethal (2) giant discs is required for the function of the ESCRT-III component Shrub/ CHMP4. JCS 125:763–776 Tsang HTH, Connell JW, Brown SE, Thompson A, Reid E, Sanderson CM (2006) A systematic analysis of human CHMP protein interactions: additional MIT domaincontaining proteins bind to multiple components of the human ESCRT III complex. Genomics 88:333–346 Usami Y, Popov S, Weiss ER, Vriesema-Magnuson C, Calistri A, Göttlinger HG (2012) Regulation of CHMP4/ESCRT-III function in human immunodeficiency virus type 1 budding by CC2D1A.  J Virol 86:3746–3756 Vaccari T, Bilder D (2005) The Drosophila tumor suppressor vps25 prevents nonautonomous overproliferation by regulating notch trafficking. Dev Cell 9:687–698 Vaccari T, Lu H, Kanwar R, Fortini M, Bilder D (2008) Endosomal entry regulates Notch receptor activation in Drosophila melanogaster. J Cell Biol 180:755–762 Vaccari T, Rusten TE, Menut L, Nezis IP, Brech A, Stenmark H, Bilder D (2009) Comparative analysis of ESCRT-I, ESCRT-II and ESCRT-III function in

T. Reiff et al. Drosophila by efficient isolation of ESCRT mutants. J Cell Sci 122:2413–2423 Vahid-Ansari F, Daigle M, Manzini MC, Tanaka KF, Hen R, Geddes SD, Béïque JC, James J, Merali Z, Albert PR (2017) Abrogated Freud-1/Cc2d1a repression of 5-HT1A autoreceptors induces fluoxetine-­ resistant anxiety/depression-like behavior. J Neurosci 37:11967–11978 Ventimiglia LN, Cuesta-Geijo MA, Martinelli N, Caballe A, Macheboeuf P, Miguet N, Parnham IM, Olmos Y, Carlton JG, Weissenhorn W, Martin-Serrano J (2018) CC2D1B coordinates ESCRT-III activity during the mitotic reformation of the nuclear envelope. Dev Cell 47:547–563 Vietri M, Radulovic M, Stenmark H (2020) The many functions of ESCRTs. Nat Rev Cell Biol 21:25–42 Wagner KU, Krempler A, Qi Y, Park K, Henry MD, Triplett AA, Riedlinger G, Rucker IEB, Hennighausen L (2003) Tsg101 is essential for cell growth, proliferation, and cell survival of embryonic and adult tissues. Mol Biol Cell 23:150–162 Weinmaster G, Fischer JA (2011) Notch ligand ubiquitylation: what is it good for? Dev Cell 21:134–144 Wilkin M, Tongngok P, Gensch N, Clemence S, Motoki M, Yamada K, Hori K, Taniguchi-Kanai M, Franklin E, Matsuno K, Baron M (2008) Drosophila HOPS and AP-3 complex genes are required for a Deltex-­ regulated activation of notch in the endosomal trafficking pathway. Dev Cell 15:762–772 Windler SL, Bilder D (2010) Endocytic internalization routes required for Delta/Notch signaling. Curr Biol 20:538–543 Yamada T, Takeuchi S, Fujita N, Nakamura A, Wang W, Li Q, Oda M, Mitsudomi T, Yatabe Y, Sekido Y, Yoshida J, Higashiyama M, Noguchi M, Uehara H, Nishioka Y, Sone S, Yano S (2013) Akt kinase-interacting protein1, a novel therapeutic target for lung cancer with EGFR-activating and gatekeeper mutations. Oncogene 32:4427–4435 Zamarbide M, Oaks AW, Pond HL, Adelman JS, Manzini MC (2018) Loss of the intellectual disability and autism gene Cc2d1a and its homolog Cc2d1b differentially affect spatial memory, anxiety, and hyperactivity. Front Genet 9:65 Zhao M, Li X-D, Chen Z (2010) CC2D!A, a DM14 and C2 domain protein, activates NF-kB through the canonical pathway. JBC 285:24372–24380


Notch and Endometrial Cancer Violeta Jonusiene and Ausra Sasnauskiene


The human endometrium is a unique, highly dynamic tissue that undergoes cyclic changes of cell proliferation, differentiation, and death. Endometrial cancer is the most common malignancy among women in developed countries. Importantly, the incidence of endometrial cancer is rising in high-income countries. Currently histological classification is used for subtyping of endometrial cancer, while ongoing research is evaluating markers for more accurate molecular classification. Evolutionary conserved Notch signaling pathway regulates diverse cellular processes such as proliferation, differentiation, and cell invasion. Accumulating evidence links aberrant Notch signaling with diseases such as hyperplasia and endometrial cancer. This chapter summarizes the current state of Notch signaling investigations in the endometrium, endometriosis, and endometrial cancer. Keywords

Notch · Endometrium · Endometrial cancer · Endometriosis · Stem cells · Leptin

V. Jonusiene (*) · A. Sasnauskiene Vilnius University, Life Sciences Center, Institute of Biosciences, Vilnius, Lithuania e-mail: [email protected]

 otch Signaling in the Normal N Endometrium The human endometrium is a unique, dynamic system that undergoes cyclic changes regulating cell proliferation, differentiation, and death during every menstrual cycle and pregnancy. Physiological changes that occur in fertile women are tightly regulated by hormones, specifically estrogen, progesterone, and chorionic gonadotropin (Banerjee and Fazleabas 2011; Maruyama and Yoshimura 2008). Therefore, it is not surprising that evolutionary conserved Notch pathway, due to its role in proliferation, differentiation, and angiogenesis, is actively involved in endometrium remodeling as well as in diseases such as hyperplasia and cancer. Morphologically the endometrium is divided into functional and basal layers. The functional layer occupies two-thirds of the endometrial thickness and it is responsible for proliferation and secretion. During menstruations, the functional layer separates from the basal layer, while the basal layer serves as a base for endometrial regeneration and remains intact during menstruation. The endometrium is composed of different compartments: the luminal and the glandular epithelium, the stroma with stromal fibroblastic cells, and the vascular compartment (Diedrich et al. 2007; Ruiz-Alonso et al. 2012). Notch is crucial for uterine development. In fact, it was shown that overexpression of

© Springer Nature Switzerland AG 2021 J. Reichrath, S. Reichrath (eds.), Notch Signaling in Embryology and Cancer, Advances in Experimental Medicine and Biology 1287,


V. Jonusiene and A. Sasnauskiene


NICD1 in mouse uterus leads to complete infertility, absence of uterine glands, and dysregulation of progesterone and estrogen signaling (Su et al. 2016). Mikhailik et al. have examined transcripts and demonstrated that Notch signaling is active in both the epithelial and stromal cells of the human endometrium. They have shown that all four NOTCH receptors are ubiquitously expressed in endometrial cells, whereas ligands JAG1 and DLL4 and targets HES1 and HEY are predominantly expressed in endometrial epithelial cells and are scarce in stromal cells. In addition, JAG1 induces Notch signaling activity in the stromal cells resulting in regulation of 452 genes (Mikhailik et al. 2009). It is important to note that this analysis was performed following cell isolation and culturing. Other investigation has demonstrated that NOTCH1 and NOTCH3 primarily localize to the glandular epithelium, whereas NOTCH4 localize to the stroma (Cobellis et al. 2008; Mitsuhashi et al. 2012). During menstrual cycle the human endometrium undergoes various phases including proliferative phase of endometrium regeneration, followed by a mid-secretory phase in which endometrial stromal fibroblasts undergo differentiation known as decidualization to secretory “epithelioid” cells and last late-secretory phase where the endometrium is shed in a nonpregnancy cycle. When menopause begins, the endometrium loses the ability to proliferate and differentiate and loses its functional layers (Salamonsen 2019; Mori et al. 2012; Evans et al. 2016). Notch pathway is active in the human endometrium and highly dynamic; expression patterns of Notch receptors and ligands are different according to cell type and menstrual cycle phase (Mikhailik et  al. 2009; Mitsuhashi et  al. 2012). Notch signaling is more active in cycling endometrium than in menopause, as the expression levels of three Notch signaling molecules, NOTCH1, NOTCH4, and JAG1, are decreased in postmenopause endometrium (Cobellis et  al. 2008). There are only a few reports regarding the role of Notch signaling in remodeling of the endometrium, and the available data is sometimes conflicting (Table 4.1). Mitsuhashi et al. have found

Table 4.1  Changes of Notch signaling molecules in cycling endometrium secretory phase compared to proliferative phase NOTCH1 NOTCH2 NOTCH3 NOTCH4 JAG1 JAG2 DLL1 DLL4

Secretory phase ↕a, b ↑c ND ↓e1↕e2 ↓c, d ↕a ↑c, e1 ND ↑e2 ↕a ↑f

a Mitsuhashi et al. (2012); bSchuring et al. (2018); cCobellis et al. (2008); dSuzuki et al. (2000); eVan Sinderen et al. (2014); fCuman et al. (2014) 1, luminal epithelium; 2, glandular epithelium; ND not determined

no cyclic changes in expression of NOTCH1, JAG1, and DLL4 proteins during menstrual cycle. Only receptor NOTCH3 expression level was increased during the secretory phase in the stroma cells. The expression of these signaling molecules was investigated predominantly in glandular cells of the normal endometrium (Mitsuhashi et al. 2012). Schuring et al. have not detected cycle-dependent changes in expression of NOTCH1 and NUMB (a negative regulator of Notch) when compared to proliferative and secretory endometrium (Schuring et  al. 2018). Meanwhile Cobelis et al. have performed immunohistochemical analysis of 60 samples of physiological endometrium (20 of each in proliferative and secretory phase and in menopause) and observed an increased expression level of NOTCH1 and JAG1  in the secretory phase and the opposite trend for NOTCH4. Authors proposed that these results indicate the role of NOTCH4  in cell proliferation as an attribute of proliferative phase of the cycle, whereas NOTCH1 possibly associates with cell differentiation as a characteristic of secretory phase in the human endometrium (Cobellis et al. 2008). These opposite results were obtained despite the fact that Mitsuhashi and Cobelis groups had used the same antibodies against NOTCH1 for immunodetection, however at different concentrations. Suzuki et al. have also shown the decreased level of NOTCH4 expression during secretory phase if

4  Notch and Endometrial Cancer

compared to the proliferative phase (Suzuki et al. 2000). The immunostaining of the endometrium has demonstrated that the expression of NOTCH1 receptor increased significantly in both glandular and luminal epithelium in the mid-secretory phase in comparison to the early- and the late-­ secretory phases. While NOTCH3 increased in the luminal epithelium during proliferative phase compared to secretory phase, no changes in expression were detected in glandular epithelium. Ligand JAG1 was detected upregulated in the luminal epithelium, and ligand DLL1 and NUMB were found in the glandular epithelium in the mid-secretory compared to the proliferative phase (Van Sinderen et  al. 2014). It has been determined that DLL4 expression increases in the secretory phase of the menstrual cycle in both glandular and luminal epithelium (Cuman et al. 2014). Previously, it has been shown that NOTCH mediates uterine stromal decidualization by preventing stromal fibroblast apoptosis and regulates gene expression and cytoskeleton reorganization in mouse (Afshar et  al. 2012). It has been revealed, by microarray studies, that NOTCH2, NOTCH3, and JAG2 are expressed by the trophectoderm (polarized transporting single cell layer) of human blastocysts (Aghajanova et al. 2012). The endometrium is involved in implantation and placental formation during establishment of pregnancy. Disorders in this process are a major reason for infertility. Critical role in implantation plays interaction of blastocyst and the endometrium. It was also demonstrated that ­ Notch signaling is involved in implantation and placentation (Cuman et  al. 2013; Cuman et  al. 2014). NOTCH1, JAG1, and DLL1 are downregulated in the endometrium of women with unexplained infertility (Van Sinderen et al. 2014).

Notch Signaling in the Endometriosis Endometriosis is a gynecological condition characterized by the growth of ectopic endometrial cells outside the uterus. This tissue similarly to eutopic endometrium undergoes regeneration


and shedding during the menstrual cycle. Endometriosis affects one in ten women of childbearing age and infertility is often associated with this disease (Hickey et  al. 2014). Endometriosis shares mechanisms of estrogen stimulation and chronic inflammation with endometrial cancer; therefore it may be associated with this type of cancer (Yu et  al. 2015). The deregulated expression components of the Notch signaling in endometriosis suggest an involvement of this pathway in the pathogenic process. Su et al. reported that Notch receptors NOTCH1 and NOTCH4, ligands JAG2 and DLL4, as well as target genes HEY1and HES5 were downregulated in eutopic endometrium of endometriosis patients suggesting that suppressed Notch signaling contributes to decidualization defects and is responsible for decreased fertility in woman with endometriosis (Su et al. 2015). NOTCH2 has also been shown as a regulator of decidualization (Otti et  al. 2014). It was demonstrated that NOTCH1, JAG1, JAG2, and survivin significantly decrease in women with endometriosis, polycystic ovary syndrome, or repeated implantation failure, concluding that Notch signaling molecule might be associated with implantations problems and poor outcomes observed in these diseases (Amjadi et  al. 2019). In addition, the expression of gene FOXO1 (NOTCH1 coactivator) was activated in decidualization. Interestingly, NOTCH1 also regulate FOXO1 expression. In the case of endometriosis, the suppression of Notch signaling results in decreased FOXO1 expression and decidualization failure (Brar et al. 2001). In contrast to the aforementioned studies, several groups have obtained opposite results. Expression of NOTCH1  in patients with deep infiltrating endometriosis and NUMB in luminal epithelium was significantly higher as compared with controls (Schuring et al. 2018). In the findings of another group, the expression levels of NOTCH1 and JAG1were upregulated in ectopic endometria than in their eutopic and normal counterparts. Moreover, estrogen regulates cell invasion in the endometriosis via activation of estrogen receptor alpha and the enhancement of Notch signaling (Li et al. 2018). After ultra-deep targeted sequencing, mutations of NOTCH1 and


NOTCH2 genes were observed in the ectopic endometrium and atypical endometriosis, but not in normal endometrium tissue (Er et al. 2016).

Endometrial Cancer Endometrial cancer (EC) is the sixth most common malignancy among women and 15th cancer in general. The rates of new diagnoses have been rising by about 1% each year. The frequency of this cancer varies among different countries – the incidence of this disease is highest in Central and Eastern Europe and North America, and it is lowest in Middle and Western Africa. Importantly, the incidence of EC is rising in high-income countries; this might be attributable to high rates of obesity, physical inactivity, late menopause, and extended life expectancy. Endometrial cancer accounts for 2% of cancer deaths in women. Fortunately, EC often causes specific symptoms at early stages, and when diagnosed at an early stage, 5-year survival rate is relatively high, reaching 69%. On the other hand, a delayed diagnosis leads to advanced stage and lower chance of survival. The majority of EC are sporadic, and 5–10% of women inherit cancer susceptibility (Sundar et  al. 2017; Amant et  al. 2018; Ferlay et al. 2018; World Cancer Research Fund 2019). Endometrial carcinoma has been traditionally classified into two histological types described by Bokhman (Bokhman 1983). Type I tumors make up 80–90% of endometrial cancers and are typically characterized by a low-grade endometrioid histology (endometrioid endometrial cancer, EEC), arising on a background of atypical hyperplasia. EEC is characterized by estrogen and progesterone receptor positivity and has a favorable prognosis in most cases. Factors leading to an excess of estrogen relative to progesterone are associated with this type of cancer (Sanderson et al. 2017; Amant et al. 2018). Type II cancer is determined in 10–20% of endometrial cancers. This type of cancer is associated with typically high-grade non-endometrioid histology (serous endometrial cancer, SEC; clear cell endometrial cancer, CCEC; uterine carcinosarcoma, UCS), arising in atrophic endometria,

V. Jonusiene and A. Sasnauskiene

and is usually estrogen independent. The precursor of lesion in this type endometrial carcinoma is not yet fully established. This cancer type has higher risk for metastases and less favorable prognosis (Pathiraja et  al. 2013; Akhtar et  al. 2019). Aside from morphologic differences between type I and type II, the endometrial cancers are distinguished by genetic alterations. The mutations of the tumor suppressor gene PTEN (phosphatase and tensin homolog) are the most frequent genetic alteration (up to 83%) in endometrioid endometrial cancer. This mutation coexists with other mutations in PIK3CA (phosphatidylinositol 3-OH kinase), CTNNB1 (which encodes β-catenin), KRAS (proto-­ oncogene, GTPase), and ARID1A (AT-rich interaction domain 1A) and defects in DNA mismatch repair. Mutations in tumor protein TP53, component of ubiquitin ligase Skp1-Cullin1-F-box complex FBXW7 (F-box with 7 tandem WD40), and PPP2R1A (protein phosphatase 2 scaffold subunit alpha) are found in non-endometrioid endometrial cancer. Other frequent alterations in this type of cancer is the overexpression of oncogene HER2/neu (erb-b2 receptor tyrosine kinase 2) and p16 (cyclin-dependent kinase inhibitor 2A, CDKN2A) loss of function leading to uncontrolled cell growth and aneuploidy (McConechy et al. 2012; Matias-Guiu and Prat 2013; O’Hara and Bell 2012). However, the accuracy of histologic classification is not sufficient in order to distribute patients into optimal treatment subgroups, since various endometrial cancer types may exhibit shared characteristics. Recently, significant progress has been made in understanding molecular events in EC, and a division of tumors into distinct prognostic groups was suggested. The Cancer Genome Atlas (TCGA) provides the most comprehensive molecular study, involving whole-­ genome sequencing, exome sequencing, MSI assay, and a copy number analysis. Endometrial cancers could be classified into four distinct groups: (1) POLE (polymerase ξ exonuclease) ultramutated, which have POLE exonuclease domain mutations; (2) MSI hypermutated tumors, which have MSI-H (microsatellite instability-­

4  Notch and Endometrial Cancer

high) status and have hypermethylated MLH1 promoter; (3) copy-number low, MSS (microsatellite stabile) tumors, characterized by a low copy number aberrations and frequent CTNNB1 mutation; and (4) and copy-number high which are characterized by high-level copy number alterations and frequent TP53 mutation. Women in POLE-mutated subgroup exhibit the best prognosis, whereas women from copy-number high subgroup have the worst prognosis in progression-free survival. This classification is currently not applied in routine clinical practice, but due to the evolution of the methodologies involved, it will, hopefully, be ready in the near future (Cancer Genome Atlas Research et  al. 2013; Urick and Bell 2019; Carlson and McCluggage 2019).

 otch Signaling in the Endometrial N Cancer Expression of Notch Signaling Components  Deregulated expression of Notch receptors and Notch ligands has been found in an increasing number of human solid tumors. However, there are only a limited number of reports of Notch signaling in the endometrial cancer. Moreover, as in the case of normal endometrium/endometriosis, the role of Notch signaling in endometrial cancer is ambiguous and seems to depend on analyzed Notch receptor/ ligand as well as on the analysis methods. For Notch signaling component expression analysis, in most cases immunohistochemical staining was used, and the expression in the endometrium was compared to normal tissue from separate patients. Suzuki et al. have published the first report about Notch signaling in endometrial cancer in 2000 (Suzuki et al. 2000). They reported that endometrial cancer cells express a significantly lower level of NOTCH4 compared to normal endometria proposing the role of NOTCH4 in endometrial cancer development. Cobellis et al. studied normal (n = 60) and pathological (n = 60) endometrium samples by immunohistochemical analysis. They detected Notch signaling changes in different normal endometrium phases. The elevated expression of NOTCH1 in hyperplasia and


carcinoma compared to polyps was found, whereas NOTCH4 and JAG1 expression decrease correlated to histological grade. In support, the expression of NOTCH1 and NOTCH4 correlated to p21 and cyclin D expression level (Cobellis et  al. 2008). Mitsuhashi et  al. demonstrated, using immunohistochemistry, the expression of NOTCH1, NOTCH3, JAG1, and DLL4 proteins was higher in endometrial cancer (n = 76) versus normal endometrium (n  =  37) from non-cancer patients. Additionally, the elevated level of NOTCH1 correlated with cancer aggressiveness such as invasion into the myometrial layer and metastasis. High expression of NOTCH1 and JAG1 was associated with poor patient’s prognosis (Mitsuhashi et  al. 2012). Mori et  al. using immunohistochemistry staining also obtained similar results that NOTCH1 expression in endometrial adenocarcinoma (n  =  21) was significantly higher than in normal endometrium (Mori et  al. 2012). When the amount of proteins NOTCH1, NOTCH3, NOTCH4, and JAG2 was determined by Western blot analysis of endometrial cancer and adjacent nontumor tissue from the same patient, the level of proteins NOTCH1 and NOTCH3 was unchanged. Meanwhile the relative amount of proteins NOTCH4 and JAG2 was decreased in the majority of stage I endometrial cancer samples, compared to nontumor endometrium of the same patient (Sasnauskiene et al. 2014). Gene expression analysis between normal and malignant patient samples showed significant elevation of JAG2 level in endometrial cancer tissues, but it has no impact on cancer patient survival (Townsend et  al. 2019). Jonusiene et  al. found the decreased expression of Notch receptors (NOTCH1, NOTCH2, NOTCH3, and NOTCH4), ligands (JAG1, JAG2, and DLL1), and Notch target gene HES1 in endometrial cancer tissue compared to normal endometrium of the same patient at mRNA level. For this analysis the samples of endometrial cancer and adjacent nontumor endometrial tissue from the same woman were used (n = 50) (Jonusiene et al. 2013). This study supports the notion that Notch signaling is less active in endometrial cancer and supposes

V. Jonusiene and A. Sasnauskiene


that it can function as tumor suppressor. In Williams et  al. investigation, it was discovered that early endometrial cancer cells lose the apicobasal polarity in the low-grade endometrial cancer. In addition, it was observed the mislocalization of Notch receptor. The decreased expression of NOTCH4 receptor, ligand JAG1, and downstream targets HES1 and HEY1 in low-grade endometrial cancer was detected by RT-PCR analysis, indicating that overall Notch signaling is suppressed in low-grade endometrial cancer, while the expression of NOTCH1 and NOTCH2 was unchanged (Williams et al. 2017). Polychronidou et al. analyzed the expression of NOTCH2, NOTCH3, and JAG1  in endometrial carcinoma tissue (n = 204) by immunostaining. It was found that more than 70% of tumor were negative for all three proteins. The study has been performed only using cancer tissues. The analysis showed that expressions of NOTCH2 and JAG1 have opposite prognostic impacts. The expression of NOTCH2 has the unfavorable prognostic impact in endometrial cancer, while JAG1 expression reflects a favorable prognosis. Moreover, expression of JAG1 was favorable in the absence NOTCH2/3 and was very similar to patients with low or undetectable expression of all three markers. The expression of NOTCH3 did not yield significant results possibly, due to small number of NOTCH3-positive patients (Polychronidou et al. 2018). The data of a retrospective study obtained from The Cancer Genome Atlas (545 tumor and 35 adjacent tissues) concluded that expression of Notch ligand DLL3 was upregulated in endometrial cancer tissues. Evaluation depends on patient age, FIGO stage, and grade. It was also discovered that upregulation of DLL3 expression was associated with the shortest overall survival in patients with endometrial cancer (Wang et  al. 2018). All available data concerning Notch signaling member’s expression in endometrial cancer are summarized in Table 4.1. All investigations coincide on the only one point: the expression levels of NOTCH4 protein and mRNA are decreased in endometrial cancer. Meanwhile, the expression status of other Notch signaling members is scarce

Table 4.2  Expression analysis of Notch signaling members in endometrial cancer NOTCH1 NOTCH2 NOTCH3 NOTCH4 JAG1 JAG2 DLL1 DLL3 DLL4 HES1 HEY1

Protein expression ↑b,c,d ↕e ND ↑c ↕e ↓a,b,e ↓b ↑c ↓e ND ND ↑c ND ND

mRNA expression ↓g ↕h ↓g ↕h ↓g ↓g,h ↓g,h ↓g ↑f ↓g ↑i ND ↓g,h ↓h

a Suzuki et al. (2000); bCobellis et al. (2008); cMitsuhashi et  al. (2012); dMori et  al. (2012); eSasnauskiene et  al. (2014); fTownsend et al. (2019); gJonusiene et al. (2013); h Williams et  al. (2017); iWang et  al. (2018); ND not determined

and sometimes contradictory, and more data are needed to draw the conclusions (Table 4.2). Stem Cells in Endometrial Cancer  A small population of adult stem cells, including epithelial progenitors, mesenchymal stem cells, and side-population cells, have been identified in the human endometrium. These cells contribute to regenerative capacity of the endometrium (Evans et al. 2016). Cancer stem cells (CSCs) are cells with stem-like properties crucial for generation of neoplastic cell population; they are responsible for invasiveness and formation of drug resistance (Hanahan and Weinberg 2011; Carvalho et al. 2015). Different molecules were studied as markers of CSC in endometrial cancer, including CD133, CD44, CD117(c-kit), and aldehyde dehydrogenase 1 (ALDH1) (Tempest et al. 2018; Giannone et al. 2019). Different signaling pathways regulate stemness in EC, including Notch signaling. The cell surface marker CD133 is known as prominin; it identifies stem-like cell population. CD133+ cells have exhibited a more aggressive proliferation in vitro and higher resistance to chemotherapeutic drugs cisplatin and paclitaxel (Elbasateeny et  al. 2016). Analysis of endometrial cancer Ishikawa cells, separated into two

4  Notch and Endometrial Cancer


CD133+and CD133− subpopulations, demonstrated the increased level of NOTCH1 protein in cancer stem-like cells CD133+. The blockade of the Notch signaling with γ-secretase inhibitor DAPT suppressed CSC proliferation. Moreover, a treatment of Ishikawa cells with DAPT and other therapeutic target, EGFR inhibitor, was more efficient than treating with any compound alone. Authors concluded that Notch signaling seems to be a promising therapeutic target for CSCs (Shang et al. 2018). Another stem cells marker in EC is RNA-­ binding protein Musashi-1. Gotte et al. found an increased protein level of Musashi-1 in endometriosis and endometrial cancer. siRNA silencing of Musashi-1 resulted in decreased expression of NOTCH1 protein and its downstream target HES1 in Ishikawa cells. At the functional level, these changes promote reduced cell proliferation and apoptosis induction (Gotte et  al. 2011). It was also shown that patients with upregulated Musashi-1 expression have poor survival rate, which may be an independent prognostic factor for endometrial cancer (Ma et al. 2015).

and migration, where leptin upregulates Notch ligands, receptors, and target genes (Guo and Gonzalez-Perez 2011). In analogy to breast cancer, the group of Gonzalez-Perez hypothesized that NILCO could be a link between obesity and endometrial cancer progression (Daley-Brown et  al. 2015). This group has demonstrated that leptin is an inducer of Notch receptors (NOTCH1– 4), ligands (JAG1 and DLL4), and downstream effectors (survivin, HEY2) and leptin (OB-R) and IL-1 (IL-1R tI) receptors in endometrial cancer cells (Daley-Brown et al. 2019). The impact of leptin was higher for the poorly differentiated and more aggressive cell lines An3Ca and KLE, resembling type II endometrial cancer. Leptin also upregulated the expression of NOTCH1, NOTCH3, and NOTCH4 receptors in the more differentiated HEC-1A and Ishikawa cells, resembling more differentiated type I endometrial cancer. Moreover, it was demonstrated that leptin induces cell cycle progression and proliferation of endometrial cancer cells. The importance of leptin signaling for endometrial cancer has to be proved using animal models.

Crosstalk of Notch and Obesity Signals  Increasing body mass index is associated with a significant increase in the risk of endometrial cancer (Reeves et al. 2007; Renehan et  al. 2008). It has been demonstrated that in comparison with all obesity-related cancers, increasing body mass index is most strongly associated with endometrial cancer incidence and mortality (Schmandt et  al. 2011). Although the correlation between obesity and cancer incidence is identified, the molecular mechanisms linking these processes remain the area of intensive studies. Obesity is characterized by excess of adipose tissue, which drives the dysregulation of complex metabolic and endocrine activities (Crean-Tate and Reizes 2018). Leptin is an adipose tissue-­ secreted hormone, which correlates with the level of adiposity and body mass index in women. Leptin signaling has been shown to induce breast cancer growth and progression (Ando et  al. 2014). It was demonstrated that Notch, IL-1, and leptin crosstalk outcome (NILCO) is involved in the induction of breast cancer cell proliferation

Mutations in Notch-Related Genes  DNA repair system plays a crucial role in recognition and repairing of insertions or deletions in microsatellites  – the repeated sequences of DNA.  Abnormal function of a repair system causes the creation of novel microsatellite fragments resulting in microsatellite instability (MSI). Some cancer types, including endometrial cancer, exhibit higher rates of MSI (16.5%). Higher rates of MSI tumor selectively share alterations in genes of common pathways including Notch and Wnt proposing possibilities of pathway-­ targeted therapies (Trabucco et  al. 2019). Mutations of NOTCH1 and NOTCH2 genes were identified in endometriosis-­associated ovarian cancer, and it may predispose endometriotic lesion to malignant transformation (Er et al. 2016). miRNAs  A class of a small noncoding RNAs, miRNAs, are important for gene regulation, and they are differentially expressed in various malignant tissues. It was identified that 138 miRNAs


are differently expressed in endometrial cancer in comparison to the normal endometrium. Among deregulated miRNAs was miR-34a, regulating members of Notch family NOTCH1, NOTCH2, JAG1, and DLL. In addition, NOTCH1 was regulated by miR-34* and miR-27b* (Jurcevic et al. 2014). Upregulation of miR-34 led to a significant decrease of NOTCH1 and DLL1 at mRNA level, while downregulation led to a significant increase in this mRNA (Jurcevic et  al. 2016). Devor et al. reported a significant downregulation of miRNA-181c in endometrial cancer. The decrease of miRNA-181c was in part attributed to upregulation of NOTCH2 (Devor et al. 2017).

Conclusion The aberrant expression of Notch signaling receptors and ligands suggests that this pathway is important for changes in cycling endometrium and in disorders such as endometriosis or endometrial cancer. There are controversial suggestions concerning the role of Notch signaling in the endometrium that are supported by sometimes contradictory results about expression changes of Notch molecules. Therefore, additional functional studies are required to reveal the importance of Notch signaling for endometrial cancer progression. Future challenges in the field include choosing of the right methods and approaches to analyze the importance of Notch signaling for endometrial cancer. It is necessary to understand how this pathway interacts with other signaling pathways, including Wnt and Hedgehog. These new studies may offer new potential markers for endometrial cancers molecular classification and prognostic or therapeutic targets.

References Afshar Y, Jeong JW, Roqueiro D, DeMayo F, Lydon J, Radtke F, Radnor R, Miele L, Fazleabas A (2012) Notch1 mediates uterine stromal differentiation and is critical for complete decidualization in the mouse. FASEB J 26(1):282–294. fj.11-184663

V. Jonusiene and A. Sasnauskiene Aghajanova L, Shen S, Rojas AM, Fisher SJ, Irwin JC, Giudice LC (2012) Comparative transcriptome analysis of human trophectoderm and embryonic stem cell-­ derived trophoblasts reveal key participants in early implantation. Biol Reprod 86(1):1–21. https://doi. org/10.1095/biolreprod.111.092775 Akhtar M, Al Hyassat S, Elaiwy O, Rashid S, Al-Nabet A (2019) Classification of endometrial carcinoma: new perspectives beyond morphology. Adv Anat Pathol 26(6):421–427. PAP.0000000000000251 Amant F, Mirza MR, Koskas M, Creutzberg CL (2018) Cancer of the corpus uteri. Int J Gynaecol Obstet 143(Suppl 2):37–50. ijgo.12612 Amjadi F, Salehi E, Zandieh Z, Rashidi M, Taleahmad S, Javedani Masrour M, Aflatoonian R, Mehdizadeh M (2019) Comparative evaluation of NOTCH signaling molecules in the endometrium of women with various gynecological diseases during the window of implantation. Iran J Basic Med Sci 22(4):426–431. https:// Ando S, Barone I, Giordano C, Bonofiglio D, Catalano S (2014) The multifaceted mechanism of leptin signaling within tumor microenvironment in driving breast cancer growth and progression. Front Oncol 4:340. Banerjee P, Fazleabas AT (2011) Extragonadal actions of chorionic gonadotropin. Rev Endocr Metab Disord 12(4):323–332. s11154-011-9193-1 Bokhman JV (1983) Two pathogenetic types of endometrial carcinoma. Gynecol Oncol 15(1):10–17. https:// Brar AK, Handwerger S, Kessler CA, Aronow BJ (2001) Gene induction and categorical reprogramming during in  vitro human endometrial fibroblast decidualization. Physiol Genomics 7(2):135–148. https://doi. org/10.1152/physiolgenomics.00061.2001 Cancer Genome Atlas Research N, Kandoth C, Schultz N, Cherniack AD, Akbani R, Liu Y, Shen H, Robertson AG, Pashtan I, Shen R, Benz CC, Yau C, Laird PW, Ding L, Zhang W, Mills GB, Kucherlapati R, Mardis ER, Levine DA (2013) Integrated genomic characterization of endometrial carcinoma. Nature 497(7447):67– 73. Carlson J, McCluggage WG (2019) Reclassifying endometrial carcinomas with a combined morphological and molecular approach. Curr Opin Oncol 31(5):411–419. Carvalho MJ, Laranjo M, Abrantes AM, Torgal I, Botelho MF, Oliveira CF (2015) Clinical translation for endometrial cancer stem cells hypothesis. Cancer Metastasis Rev 34(3):401–416. https://doi. org/10.1007/s10555-015-9574-0 Cobellis L, Caprio F, Trabucco E, Mastrogiacomo A, Coppola G, Manente L, Colacurci N, De Falco M, De Luca A (2008) The pattern of expression of Notch protein members in normal and pathological

4  Notch and Endometrial Cancer endometrium. J Anat 213(4):464–472. https://doi. org/10.1111/j.1469-7580.2008.00963.x Crean-Tate KK, Reizes O (2018) Leptin regulation of cancer stem cells in breast and gynecologic Cancer. Endocrinology 159(8):3069–3080. https://doi. org/10.1210/en.2018-00379 Cuman C, Menkhorst EM, Rombauts LJ, Holden S, Webster D, Bilandzic M, Osianlis T, Dimitriadis E (2013) Preimplantation human blastocysts release factors that differentially alter human endometrial epithelial cell adhesion and gene expression relative to IVF success. Hum Reprod 28(5):1161–1171. https://doi. org/10.1093/humrep/det058 Cuman C, Menkhorst E, Winship A, Van Sinderen M, Osianlis T, Rombauts LJ, Dimitriadis E (2014) Fetal-­ maternal communication: the role of Notch signalling in embryo implantation. Reproduction 147(3):R75– R86. Daley-Brown D, Oprea-Ilies GM, Lee R, Pattillo R, Gonzalez-Perez RR (2015) Molecular cues on obesity signals, tumor markers and endometrial cancer. Horm Mol Biol Clin Invest 21(1):89–106. https://doi. org/10.1515/hmbci-2014-0049 Daley-Brown D, Harbuzariu A, Kurian AA, Oprea-Ilies G, Gonzalez-Perez RR (2019) Leptin-induced Notch and IL-1 signaling crosstalk in endometrial adenocarcinoma is associated with invasiveness and chemoresistance. World J Clin Oncol 10(6):222–233. https:// Devor EJ, Miecznikowski J, Schickling BM, Gonzalez-­ Bosquet J, Lankes HA, Thaker P, Argenta PA, Pearl ML, Zweizig SL, Mannel RS, Brown A, Ramirez NC, Ioffe OB, Park KJ, Creasman WT, Birrer MJ, Mutch D, Leslie KK (2017) Dysregulation of miR-181c expression influences recurrence of endometrial endometrioid adenocarcinoma by modulating NOTCH2 expression: an NRG Oncology/Gynecologic Oncology Group study. Gynecol Oncol 147(3):648–653. https:// Diedrich K, Fauser BC, Devroey P, Griesinger G, Evian Annual Reproduction Workshop G (2007) The role of the endometrium and embryo in human implantation. Hum Reprod Update 13(4):365–377. https://doi. org/10.1093/humupd/dmm011 Elbasateeny SS, Salem AA, Abdelsalam WA, Salem RA (2016) Immunohistochemical expression of cancer stem cell related markers CD44 and CD133 in endometrial cancer. Pathol Res Pract 212(1):10–16. https:// Er TK, Su YF, Wu CC, Chen CC, Wang J, Hsieh TH, Herreros-Villanueva M, Chen WT, Chen YT, Liu TC, Chen HS, Tsai EM (2016) Targeted next-generation sequencing for molecular diagnosis of endometriosis-­ associated ovarian cancer. J Mol Med 94(7):835–847. Evans J, Salamonsen LA, Winship A, Menkhorst E, Nie G, Gargett CE, Dimitriadis E (2016) Fertile ground: human endometrial programming and lessons in health and disease. Nat Rev Endocrinol 12(11):654– 667.

55 Ferlay J, Colombet M, Soerjomataram I, Dyba T, Randi G, Bettio M, Gavin A, Visser O, Bray F (2018) Cancer incidence and mortality patterns in Europe: estimates for 40 countries and 25 major cancers in 2018. Eur J Cancer 103:356–387. ejca.2018.07.005 Giannone G, Attademo L, Scotto G, Genta S, Ghisoni E, Tuninetti V, Aglietta M, Pignata S, Valabrega G (2019) Endometrial cancer stem cells: role, characterization and therapeutic implications. Cancers 11(11). https:// Gotte M, Greve B, Kelsch R, Muller-Uthoff H, Weiss K, Kharabi Masouleh B, Sibrowski W, Kiesel L, Buchweitz O (2011) The adult stem cell marker Musashi-1 modulates endometrial carcinoma cell cycle progression and apoptosis via Notch-1 and p21WAF1/CIP1. In J Cancer 129(8):2042–2049. Guo S, Gonzalez-Perez RR (2011) Notch, IL-1 and leptin crosstalk outcome (NILCO) is critical for leptin-­ induced proliferation, migration and VEGF/VEGFR-2 expression in breast cancer. PLoS One 6(6):e21467. Hanahan D, Weinberg RA (2011) Hallmarks of cancer: the next generation. Cell 144(5):646–674. https://doi. org/10.1016/j.cell.2011.02.013 Hickey M, Ballard K, Farquhar C (2014) Endometriosis. BMJ 348:g1752. Jonusiene V, Sasnauskiene A, Lachej N, Kanopiene D, Dabkeviciene D, Sasnauskiene S, Kazbariene B, Didziapetriene J (2013) Down-regulated expression of Notch signaling molecules in human endometrial cancer. Med Oncol 30(1):438. s12032-012-0438-y Jurcevic S, Olsson B, Klinga-Levan K (2014) MicroRNA expression in human endometrial adenocarcinoma. Cancer Cell Int 14(1):88. s12935-014-0088-6 Jurcevic S, Klinga-Levan K, Olsson B, Ejeskar K (2016) Verification of microRNA expression in human endometrial adenocarcinoma. BMC Cancer 16:261. https:// Li N, Zhang L, Li Q, Du Y, Liu H, Liu Y, Xiong W (2018) Notch activity mediates oestrogen-induced stromal cell invasion in endometriosis. Reproduction 157(4):371– 381. Ma L, Xu YL, Ding WJ, Shao HF, Teng YC (2015) Prognostic value of Musashi-1 in endometrioid adenocarcinoma. Int J Clin Exp Pathol 8(5):4564–4572 Maruyama T, Yoshimura Y (2008) Molecular and cellular mechanisms for differentiation and regeneration of the uterine endometrium. Endocr J 55(5):795–810. Matias-Guiu X, Prat J (2013) Molecular pathology of endometrial carcinoma. Histopathology 62(1):111– 123. McConechy MK, Ding J, Cheang MC, Wiegand K, Senz J, Tone A, Yang W, Prentice L, Tse K, Zeng T, McDonald H, Schmidt AP, Mutch DG, McAlpine JN, Hirst M, Shah SP, Lee CH, Goodfellow PJ, Gilks

56 CB, Huntsman DG (2012) Use of mutation profiles to refine the classification of endometrial carcinomas. J Pathol 228(1):20–30. path.4056 Mikhailik A, Mazella J, Liang S, Tseng L (2009) Notch ligand-dependent gene expression in human endometrial stromal cells. Biochem Biophys Res Commun 388(3):479–482. bbrc.2009.07.037 Mitsuhashi Y, Horiuchi A, Miyamoto T, Kashima H, Suzuki A, Shiozawa T (2012) Prognostic significance of Notch signalling molecules and their involvement in the invasiveness of endometrial carcinoma cells. Histopathology 60(5):826–837. https://doi. org/10.1111/j.1365-2559.2011.04158.x Mori M, Miyamoto T, Ohno S, Miyake Y, Sakaguchi T, Ohno E (2012) Diagnostic utility of notch-1 immunocytochemistry in endometrial cytology. Acta Cytol 56(2):166–170. O'Hara AJ, Bell DW (2012) The genomics and genetics of endometrial cancer. Adv Genom Genet 2012(2):33– 47. Otti GR, Saleh L, Velicky P, Fiala C, Pollheimer J, Knofler M (2014) Notch2 controls prolactin and insulin-like growth factor binding protein-1 expression in decidualizing human stromal cells of early pregnancy. PLoS One 9(11):e112723. pone.0112723 Pathiraja P, Dhar S, Haldar K (2013) Serous endometrial intraepithelial carcinoma: a case series and literature review. Cancer Manag Res 5:117–122. https://doi. org/10.2147/CMAR.S45141 Polychronidou G, Kotoula V, Manousou K, Kostopoulos I, Karayannopoulou G, Vrettou E, Bobos M, Raptou G, Efstratiou I, Dionysopoulos D, Chatzopoulos K, Lakis S, Chrisafi S, Tsolakidis D, Papanikolaou A, Dombros N, Fountzilas G (2018) Mismatch repair deficiency and aberrations in the Notch and Hedgehog pathways are of prognostic value in patients with endometrial cancer. PLoS One 13(12):e0208221. https://doi. org/10.1371/journal.pone.0208221 Reeves GK, Pirie K, Beral V, Green J, Spencer E, Bull D, Million Women Study C (2007) Cancer incidence and mortality in relation to body mass index in the Million Women Study: cohort study. BMJ 335(7630):1134. Renehan AG, Tyson M, Egger M, Heller RF, Zwahlen M (2008) Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies. Lancet 371(9612):569–578. Ruiz-Alonso M, Blesa D, Simon C (2012) The genomics of the human endometrium. Biochim Biophys Acta 1822(12):1931–1942. bbadis.2012.05.004 Salamonsen LA (2019) WOMEN IN REPRODUCTIVE SCIENCE: my WOMBan’s life: understanding human endometrial function. Reproduction 158(6):F55–F67.

V. Jonusiene and A. Sasnauskiene Sanderson PA, Critchley HO, Williams AR, Arends MJ, Saunders PT (2017) New concepts for an old problem: the diagnosis of endometrial hyperplasia. Hum Reprod Update 23(2):232–254. humupd/dmw042 Sasnauskiene A, Jonusiene V, Krikstaponiene A, Butkyte S, Dabkeviciene D, Kanopiene D, Kazbariene B, Didziapetriene J (2014) NOTCH1, NOTCH3, NOTCH4, and JAG2 protein levels in human endometrial cancer. Medicina 50(1):14–18. https://doi. org/10.1016/j.medici.2014.05.002 Schmandt RE, Iglesias DA, Co NN, Lu KH (2011) Understanding obesity and endometrial cancer risk: opportunities for prevention. Am J Obstet Gynecol 205(6):518–525. ajog.2011.05.042 Schuring AN, Dahlhues B, Korte A, Kiesel L, Titze U, Heitkotter B, Ruckert C, Gotte M (2018) The endometrial stem cell markers notch-1 and numb are associated with endometriosis. Reprod Biomed Online 36(3):294–301. rbmo.2017.11.010 Shang C, Lang B, Meng LR (2018) Blocking NOTCH pathway can enhance the effect of EGFR inhibitor through targeting CD133+ endometrial cancer cells. Cancer Biol Ther 19(2):113–119. 080/15384047.2016.1250985 Su RW, Strug MR, Joshi NR, Jeong JW, Miele L, Lessey BA, Young SL, Fazleabas AT (2015) Decreased Notch pathway signaling in the endometrium of women with endometriosis impairs decidualization. J Clin Endocrinol Metab 100(3):E433–E442. https://doi. org/10.1210/jc.2014-3720 Su RW, Strug MR, Jeong JW, Miele L, Fazleabas AT (2016) Aberrant activation of canonical Notch1 signaling in the mouse uterus decreases progesterone receptor by hypermethylation and leads to infertility. Proc Natl Acad Sci U S A 113(8):2300–2305. https:// Sundar S, Balega J, Crosbie E, Drake A, Edmondson R, Fotopoulou C, Gallos I, Ganesan R, Gupta J, Johnson N, Kitson S, Mackintosh M, Martin-Hirsch P, Miles T, Rafii S, Reed N, Rolland P, Singh K, Sivalingam V, Walther A (2017) BGCS uterine cancer guidelines: recommendations for practice. Eur J Obstet Gynecol Reprod Biol 213:71–97. ejogrb.2017.04.015 Suzuki T, Aoki D, Susumu N, Udagawa Y, Nozawa S (2000) Imbalanced expression of TAN-1 and human Notch4 in endometrial cancers. Int J Oncol 17(6):1131– 1139. Tempest N, Maclean A, Hapangama DK (2018) Endometrial stem cell markers: current concepts and unresolved questions. Int J Mol Sci 19(10). https://doi. org/10.3390/ijms19103240 Townsend MH, Ence ZE, Felsted AM, Parker AC, Piccolo SR, Robison RA, O’Neill KL (2019) Potential new biomarkers for endometrial cancer. Cancer Cell Int 19:19.

4  Notch and Endometrial Cancer Trabucco SE, Gowen K, Maund SL, Sanford E, Fabrizio DA, Hall MJ, Yakirevich E, Gregg JP, Stephens PJ, Frampton GM, Hegde PS, Miller VA, Ross JS, Hartmaier RJ, Huang SA, Sun JX (2019) A novel next-­ generation sequencing approach to detecting microsatellite instability and pan-tumor characterization of 1000 microsatellite instability-high cases in 67,000 patient samples. J Mol Diagnost 21(6):1053–1066. Urick ME, Bell DW (2019) Clinical actionability of molecular targets in endometrial cancer. Nat Rev Cancer 19(9):510–521. s41568-019-0177-x Van Sinderen M, Cuman C, Gamage T, Rainczuk K, Osianlis T, Rombauts L, Dimitriadis E (2014) Localisation of the Notch family in the human endometrium of fertile and infertile women. J Mol Histol 45(6):697–706. s10735-014-9587-y Wang J, Zhang K, Liu Z, Wang T, Shi F, Zhang Y, Su J, Jia Y (2018) Upregulated delta-like protein 3 expression

57 is a diagnostic and prognostic marker in endometrial cancer: a retrospective study. Medicine 97(51):e13442. Williams E, Villar-Prados A, Bowser J, Broaddus R, Gladden AB (2017) Loss of polarity alters proliferation and differentiation in low-grade endometrial cancers by disrupting Notch signaling. PLoS One 12(12):e0189081. pone.0189081 World Cancer Research Fund. dietandcancer/cancertrends/endometrial-cancer-statistics. Accessed October 23, 2019 Yu HC, Lin CY, Chang WC, Shen BJ, Chang WP, Chuang CM, Task Force on Carcinogenesis of Endometrial C (2015) Increased association between endometriosis and endometrial cancer: a nationwide population-­ based retrospective cohort study. Int J Gynecol Cancer 25(3):447–452. IGC.0000000000000384


NOTCH and Esophageal Squamous Cell Carcinoma Yong Li, Yahui Li, and Xiaoxin Chen


Esophageal squamous cell carcinoma (ESCC) is a deadly disease that requires extensive research on its mechanisms, prevention, and therapy. Recent studies have shown that NOTCH mutations are commonly seen in human ESCC.  This chapter summarizes our current understanding of the NOTCH pathway in normal esophagus and in ESCC. In normal

Y. Li Department of Thoracic Surgery, National Cancer Center, Cancer Hospital of Chinese Academy of Medical Sciences, Beijing, China Cancer Research Program, Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA Y. Li Cancer Research Program, Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA X. Chen (*) Cancer Research Program, Julius L. Chambers Biomedical Biotechnology Research Institute, North Carolina Central University, Durham, NC, USA Center for Gastrointestinal Biology and Disease, Division of Gastroenterology and Hepatology, Department of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA e-mail: [email protected]

esophagus, NOTCH pathway regulates the development of esophageal squamous epithelium, in particular, squamous differentiation. Exposure to extrinsic and intrinsic factors, such as gastroesophageal reflux, alcohol drinking, and inflammation, downregulates the NOTCH pathway and thus inhibits squamous differentiation of esophageal squamous epithelial cells. In ESCC, NOTCH plays a dual role as both a tumor suppressor pathway and an oncogenic pathway. In summary, further studies are warranted to develop NOTCH activators for the prevention of ESCC and NOTCH inhibitors for targeted therapy of a subset of ESCC with activated NOTCH pathway. Keywords

NOTCH · Esophagus · Esophageal squamous cell carcinoma

Abbreviations 4NQO 4-nitroquinoline 1-oxide BE Barrett’s esophagus ESCC esophageal squamous cell carcinoma HNSCC head and neck squamous cell carcinoma SCC squamous cell carcinoma

© Springer Nature Switzerland AG 2021 J. Reichrath, S. Reichrath (eds.), Notch Signaling in Embryology and Cancer, Advances in Experimental Medicine and Biology 1287,



Introduction Esophageal cancer affected 17,290 adults and caused 15,850 deaths in the USA in 2018 (Cancer Facts & Figs. 2018). In the world, it is the seventh most prevalent cancer and the sixth leading cause of cancer-related death, with more than 572,000 new cases and 508,000 deaths each year (Bray et al. 2018; Siegel et al. 2017). Two main histological types of esophageal cancer exist, squamous cell carcinoma (SCC) and adenocarcinoma. Human esophageal squamous cell carcinoma (ESCC) develops from precancerous lesions, and its histopathology follows a stepwise pattern of hyperplasia, dysplasia, and SCC. The 5-year survival rate for ESCC is ~18%, a number that reflects late diagnosis, the aggressiveness of the disease, and a lack of effective treatment strategies (Kang et al. 2015; Liu et al. 2016a). Thus, there is a great need to further elucidate the molecular mechanisms and develop better preventive and therapeutic strategies for ESCC. Recent technological advances in NextGen sequencing enabled the detection of gene mutations in human ESCC samples (Agrawal et  al. 2012; Gao et al. 2014; Lin et al. 2014; Liu et al. 2016b, 2017; Qin et al. 2016; Sawada et al. 2016; Shibata et al. 2011; Song et al. 2014; Zhang et al. 2015). Common genomic alterations included single nucleotide variants, copy number alterations, and alterations in multiple signaling pathways. The overall mutation pattern appeared similar to that of head and neck SCC (HNSCC) but distinct from that of esophageal adenocarcinoma and lung SCC. Genes on the NOTCH pathway were frequently mutated in human ESCC (Kang et al. 2015; Liu et al. 2016a). This observation brings about interesting questions regarding the functional role of the NOTCH pathway in the development of ESCC.

NOTCH in Normal Esophagus NOTCH pathway is mediated through ligands (JAG1, JAG2, DLL1, DLL3, DLL4) binding to NOTCH receptors (NOTCH1, 2, 3, 4). These receptors are then cleaved to allow its i­ ntracellular

Y. Li et al.

domain (e.g., NICD1) to be released from the membrane and enter the nucleus to form a transcriptional complex with RBPJ. NICD1 displaces the repressive cofactors bound to RBPJ and recruits a transcriptional activator complex, which initiates transcription of NOTCH downstream effectors like HES1 (Borggrefe and Oswald 2009). In the normal esophagus of rodents and humans, NOTCH1, NOTCH2, and NOTCH3 are highly expressed, whereas NOTCH4 is expressed at a minimal level (Sander and Powell 2004; Zhang et al. 2018). NOTCH3 expression was found to be subject to transcriptional regulation by NOTCH1, and loss of NOTCH signaling in mouse esophagus resulted in NOTCH3 silence (Ohashi et  al. 2010). Nevertheless, NOTCH pathway is largely dispensable for maintaining the integrity of squamous epithelium. Although NOTCH1 is the major regulator of squamous differentiation among four NOTCH receptors, even in triple knockout mice (Notch1, Notch2, Notch3), the epidermis still formed almost normally except for the phenotypes of squamous hyperplasia and deficient barrier function (Demehri et al. 2009). Regulation of Squamous Differentiation by NOTCH  NOTCH regulates squamous differentiation in the skin (Okuyama et al. 2008) and the esophagus (Ohashi et  al. 2010; Ohashi et  al. 2011), particularly in the commitment of keratinocytes to terminal differentiation by a HES1-­ dependent mechanism (Blanpain et  al. 2006; Wang et  al. 2008). Not surprisingly, NOTCH interacts with key regulators of squamous differentiation, such as P63 (Tadeu and Horsley 2013), IRF6 (Restivo et al. 2011), NRF2 (Wakabayashi et al. 2013; Wakabayashi et al. 2010), and HPV8 E6 (Meyers et al. 2013). Using gene microarray data of mouse esophagus at various developmental stages and ages, we found the NOTCH pathway participates in the development of mouse esophageal epithelium (Chen et al. 2012). Further studies have shown that NOTCH is required for the specification of esophageal progenitor cells from human progenitor stem cells. In agreement with these observations, genetic deficiency of NOTCH components (Rbpj, Jag1, Jag2) inhib-


ited squamous differentiation in mouse esophagus (Zhang et al. 2018). NOTCH Mutations in Normal Esophagus  It is surprising that NOTCH1, NOTCH2, and NOTCH3 mutations occurred much more often in physiologically normal human esophageal epithelia (66.2% samples) than in ESCC (15% samples), and distribution pattern of the mutation sites was similar in normal and ESCC samples. Human subjects with ESCC risk factors (alcohol drinking, tobacco smoking, aging) were more likely to carry NOTCH mutations than those without these risk factors (Yokoyama et al. 2019; Martincorena et  al. 2018; Yizhak et  al. 2019). However, few of the mutations were present in all the cells of the normal clones, and many of the NOTCH mutations were found in spatially distinct subclones. These data suggest that NOTCH mutations are not sufficient to drive carcinogenesis, and some other mutations are needed. NOTCH mutations can be either driver or passenger mutations in human ESCC (Chanock 2018; Ciccarelli 2019). Why normal esophageal epithelial cells are susceptible to NOTCH mutations? A recent report based solely on cancer genome sequencing and epidemiological data estimated that DNA replication errors may contribute to 38.9% gene mutations in ESCC, while hereditary mutations and environmental factors contribute to 0.5% and 60.6% mutations, respectively (Tomasetti et  al. 2017a). This was believed to be due to a relatively high rate of stem cell division in the esophagus although debates still remain (Wu et  al. 2016; Tomasetti et al. 2017b). Interestingly, there was a significant decrease in the rate of stem cell division in the human esophagus with age. In contrast, only a small decrease was observed in the mouse esophagus. These data provide a plausible explanation for the enigmatic age-­dependent deceleration in cancer incidence in very old humans but not in mice (Tomasetti et al. 2019). Response of the NOTCH Pathway to Gastroesophageal Reflux  Regurgitation of ­gastric and duodenal contents (e.g., acid and bile acids) into the esophagus causes heartburn and


leads to substantial impairment of quality of life and work productivity. Some subjects with gastroesophageal reflux are further complicated with Barrett’s esophagus (BE) when histologic evidence of intestinal metaplasia is present in the human esophageal epithelium. Acid and bile acids inhibited the NOTCH pathway in esophageal squamous epithelial cells (Wang et al. 2018; Yuan et al. 2017; Morrow et al. 2009), supporting an essential role of the NOTCH pathway in squamous differentiation. Moreover, inhibition of the NOTCH pathway favored goblet cell differentiation, which is diagnostic of human BE. Treatment of a rat model of reflux-induced BE with a γ-secretase inhibitor converted the proliferative Barrett’s epithelial cells into terminally differentiated goblet cells, whereas the squamous epithelium remained intact (Menke et al. 2010). When human esophageal squamous epithelial cells were stably transfected with an intestinal transcription factor, CDX2, these cells formed crypt-­ like structures, overexpressed differentiation markers of intestinal columnar epithelial cells and goblet cells, and downregulated NOTCH pathway genes (Liu et al. 2007). These data support NOTCH inhibition as one of the molecular mechanisms of human BE as a result of exposure to gastroesophageal reflux (Chen et al. 2011). Response of the NOTCH Pathway to Alcohol Drinking  NOTCH pathway was inhibited by ethanol in the pancreas and smooth muscle cells (Schneider et  al. 2012; Morrow et  al. 2010). Mechanistically, ethanol suppressed the NOTCH pathway through inhibition of γ-secretase proteolytic activity (Hatch et al. 2015). In the esophagus, we first found out that ethanol exposure downregulated PAX9 expression in human esophageal epithelial cells in  vitro and mouse forestomach and tongue in  vivo (Xiong et  al. 2018). More importantly, PAX9 was found to be a downstream effector of the NOTCH pathway in esophageal squamous epithelial cells, and ethanol exposure inhibited the NOTCH pathway as well (unpublished data). Consistent with the function of NOTCH in squamous differentiation, we also showed that Pax9 deficiency in mouse esophagus promoted cell proliferation and


delayed cell differentiation, and PAX9 was downregulated in human ESCC (Xiong et  al. 2018). Response of the NOTCH Pathway to Inflammation  Inflammatory cytokines (IL4, IL5, IL1, TNFα) suppressed NOTCH-dependent transcription, NOTCH ligands, and NOTCH1 target genes in human esophageal epithelial cells. These changes contributed to the development of eosinophilic esophagitis and possibly inflammation-­ associated ESCC (Kasagi et  al. 2018).

NOTCH in ESCC NOTCH Mutations in ESCC  Based on the original data from 2 studies of 227 cases of human ESCC (Lin et  al. 2014; Song et  al. 2014), NOTCH1, NOTCH2, and NOTCH3 mutations took place in 8%, 3%, and 1.9% of human ESCC, respectively. Point mutations tended to cluster in the EGF-like repeats and thus potentially resulted in the loss of function (Fig.  5.1a–c). These mutations tended to be mutually exclusive (Fig.  5.1d). RBPJ (a key repressor of canonical NOTCH pathway) and FBXW7 (the substrate-recognition subunit of an SCF-type ubiquitin ligase complex targeting NOTCH1) were also frequently mutated (Chang et al. 2017; Cheng et al. 2016). It was interesting that NOTCH1 mutation was mutually exclusive with PIK3CA mutation. NOTCH1 mutation was associated with well-differentiated, early-stage malignancy and less metastasis to regional lymph nodes. Patients with NOTCH mutations tended to have a worse prognosis than those without (Fig. 5.2). In contrast, patients with PIK3CA mutations had better response to chemotherapy and longer survival time than those without (Song et  al. 2016). Moreover, lower expression of NOTCH1 was associated with poorer prognosis than higher expression after adjustment for age, sex, tumor stage, smoking, and alcohol consumption (Qin et al. 2016).

Y. Li et al.

NOTCH as a Tumor Suppressor Pathway  In the normal esophagus, NOTCH functions as a tumor suppressor (Nowell and Radtke 2017). Exposure to an oro-esophageal carcinogen, 4-nitroquinoline 1-oxide (4NQO), caused loss of NOTCH1 expression in the basal cells of normal esophageal squamous epithelium, as well as Notch1 mutations. Loss of Notch1 in the squamous epithelial cells caused spontaneous SCC in the skin, but not the esophagus. However, loss of Notch1 promoted 4NQO-induced oro-­esophageal SCC (Nyman et  al. 2018; Sawangarun et  al. 2018). Similarly, NOTCH inhibition in mouse esophagus increased the number and size of tumors following exposure to an esophageal carcinogen, diethylnitrosamine (Alcolea et al. 2014). Using the lineage tracing technique in mice carrying a conditional dominant-negative mutant of Maml1 (a transcriptional coactivator for NOTCH), Alcolea et al. found that NOTCH inhibition prevented differentiation of mutant progenitor cells and promoted differentiation of neighboring wild-type progenitor cells in mouse esophagus (Alcolea et al. 2014). Such combined effects led to clonal expansion with mutant cells eventually replacing the entire epithelium, supporting the idea that NOTCH mutation promotes field change in the human esophageal epithelium (Yokoyama et al. 2019; Martincorena et al. 2018; Yizhak et al. 2019). NOTCH as an Oncogenic Pathway  However, the NOTCH pathway plays a dual role in carcinogenesis, both oncogenic and tumor suppressor, depending on the cellular and genetic context (Nowell and Radtke 2017; Lobry et  al. 2011; Ranganathan et al. 2011; Zhong et al. 2015; Sun et al. 2014). It is believed that NOTCH pathway turns to be oncogenic during the process of carcinogenesis. In ESCC, cellular senescence checkpoint functions (e.g., P16-Rb, P14, P53) determined differential NOTCH1-dependent oncogenic and tumor suppressor activities (Kagawa et  al. 2015). Activated NOTCH1 was detected in a small subset of cancer cells at the invasive front in human ESCC, which correlated with higher tumor aggressiveness. NOTCH1



Fig. 5.1  NOTCH mutations in human ESCC. These plots are downloaded from the TCGA database ( based on the original data from 2 studies of 227 cases of human ESCC (Lin et al. 2014; Song et al. 2014).

EGF-LR, epidermal growth factor-like repeat; LNR, LIN12-NOTCH repeat; NOD and NODP, NOTCH protein domain; ANK, ankyrin repeats; DUF, domain of unknown function

facilitated not only epithelial-mesenchymal transition but also TGFβ-mediated tumor initiation by increasing the number of cancer stem cells (Natsuizaka et al. 2017).

RBPJ acted as a tumor-promoting function in HNSCC (Al Labban et al. 2018).

Conclusion Similar to ESCC, NOTCH activity is contextual, and NOTCH in HNSCC is considered to have a dual role as a tumor suppressor and an oncogene (Fukusumi and Califano 2018), at least in a subset of HNSCC based on genomics data (Sun et  al. 2014). NOTCH4-HEY1 pathway induced epithelial-mesenchymal transition in cultured cells (Fukusumi et al. 2018). Both deficiency and activation of Notch1 promoted oral squamous cell carcinogenesis in a genetic model driven by HPV E6/E7 and KrasG12D (Zhong et al. 2015). Inactivation of the NOTCH pathway by a dominant-negative form of Maml1 promoted HNSCC induced by 4NQO, especially in the presence of p53 mutation or HPV16 E6/E7 oncoproteins (Nyman et al. 2018). On the other hand,

Considering its function as a tumor suppressor, NOTCH activators may be used for the prevention of ESCC. Chemical NOTCH activators, e.g., resveratrol, valproic acid, chrysin, hesperetin, thiocoraline, and N-methylhemeanthidine chloride (Wyche et al. 2014; Patel et al. 2014; Yu et al. 2013; Pinchot et al. 2011; Greenblatt et al. 2007; Ye et  al. 2016), may be further tested for their protective effect on ESCC. Other than chemical NOTCH activator, a NOTCH3 antibody is also known to activate NOTCH (Li et  al. 2008). NOTCH activation may also be achieved through inhibition of negative regulators of the NOTCH pathway, such as FBXW7 or NUMB.  On the other hand, NOTCH inhibition needs to be

Y. Li et al.


100% 90% 80%

Overall Survival

70% 60% 50% 40% 30% 20%

Logrank Test P-Value: 0.136 Cases with Alteration(s) in Query Gene(s) Cases without Alteration(s) in Query Gene(s)

10% 0%












Months Survival No. of Cases (Total)

No. of Cases (Deceased)

Median Survival (Months)

Cases with mutation




Cases w/o mutation




Fig. 5.2  NOTCH mutations and prognosis of human ESCC. The plot is downloaded from the TCGA database (www. based on the survival data from 1 study of 88 cases of human ESCC (Song et al. 2014)

explored as a potential therapy for a subset of ESCC with activated NOTCH pathway. It should be noted that the NOTCH pathway is complicated in the esophagus just like in many other organs. NOTCH pathway in the normal esophagus behaves differently from that in ESCC. NOTCH target genes in the normal esophagus and those in ESCC need to be identified for functional characterization of the NOTCH pathway in these contexts. Moreover, it remains to be elucidated how NOTCH pathway discriminates between distinct ligands as well as receptors in these contexts (Nandagopal et  al. 2018). If we further consider NOTCH pathway in the tumor microenvironment (Meurette and Mehlen 2018) and noncanonical NOTCH pathway (Steinbuck and Winandy 2018), it is obvious that a lot more

studies are warranted to elucidate the sophisticated role of the NOTCH pathway in ESCC.

References Agrawal N, Jiao Y, Bettegowda C, Hutfless SM, Wang Y, David S et al (2012) Comparative genomic analysis of esophageal adenocarcinoma and squamous cell carcinoma. Cancer Discov 2(10):899–905. PubMed PMID: 22877736. Pubmed Central PMCID: 3473124. Epub 2012/08/11. eng Al Labban D, Jo SH, Ostano P, Saglietti C, Bongiovanni M, Panizzon R et al (2018) Notch-effector CSL promotes squamous cell carcinoma by repressing histone demethylase KDM6B.  J Clin Invest 128(6):2581– 2599. PubMed PMID: 29757189. Pubmed Central PMCID: 5983322 Alcolea MP, Greulich P, Wabik A, Frede J, Simons BD, Jones PH (2014) Differentiation imbalance in single oesophageal progenitor cells causes clonal immortal-

5  NOTCH and ESCC ization and field change. Nat Cell Biol 16(6):615–622. PubMed PMID: 24814514. Pubmed Central PMCID: 4085550 Blanpain C, Lowry WE, Pasolli HA, Fuchs E (2006) Canonical notch signaling functions as a commitment switch in the epidermal lineage. Genes Dev 20(21):3022–3035. PubMed PMID: 17079689. Pubmed Central PMCID: 1620020. Epub 2006/11/03. eng Borggrefe T, Oswald F (2009) The Notch signaling pathway: transcriptional regulation at Notch target genes. Cell Mol Life Sci 66(10):1631–1646. PubMed PMID: 19165418. Epub 2009/01/24. eng Bray F, Ferlay J, Soerjomataram I, Siegel RL, Torre LA, Jemal A (2018) Global cancer statistics 2018: GLOBOCAN estimates of incidence and mortality worldwide for 36 cancers in 185 countries. CA Cancer J Clin 68(6):394–424. PubMed PMID: 30207593 Chang J, Tan W, Ling Z, Xi R, Shao M, Chen M et  al (2017) Genomic analysis of oesophageal squamous-­ cell carcinoma identifies alcohol drinking-related mutation signature and genomic alterations. Nat Commun 8:15290. PubMed PMID: 28548104. Pubmed Central PMCID: 5477513 Chanock SJ (2018) The paradox of mutations and cancer. Science 362(6417):893–894. PubMed PMID: 30467157 Chen H, Fang Y, Tevebaugh W, Orlando RC, Shaheen NJ, Chen X (2011) Molecular mechanisms of Barrett’s esophagus. Dig Dis Sci 56(12):3405–3420. PubMed PMID: 21984436. Pubmed Central PMCID: 3750118 Chen H, Li J, Li H, Hu Y, Tevebaugh W, Yamamoto M et  al (2012) Transcript profiling identifies dynamic gene expression patterns and an important role for Nrf2/Keap1 pathway in the developing mouse esophagus. PLoS One 7(5):e36504. PubMed PMID: 22567161. Pubmed Central PMCID: 3342176. Epub 2012/05/09. eng Cheng C, Cui H, Zhang L, Jia Z, Song B, Wang F et al (2016) Genomic analyses reveal FAM84B and the NOTCH pathway are associated with the progression of esophageal squamous cell carcinoma. GigaScience 5:1. PubMed PMID: 26759717. Pubmed Central PMCID: 4709967 Ciccarelli FD (2019) Mutations differ in normal and cancer cells of the oesophagus. Nature 565(7739):301– 303. PubMed PMID: 30643303 Demehri S, Turkoz A, Kopan R (2009) Epidermal Notch1 loss promotes skin tumorigenesis by impacting the stromal microenvironment. Cancer Cell 16(1):55–66. PubMed PMID: 19573812. Pubmed Central PMCID: 2705757 Fukusumi T, Califano JA (2018) The NOTCH pathway in head and neck squamous cell carcinoma. J Dent Res 97(6):645–653. PubMed PMID: 29489439. Pubmed Central PMCID: 5960881 Fukusumi T, Guo TW, Sakai A, Ando M, Ren S, Haft S et  al (2018) The NOTCH4-HEY1 pathway induces epithelial-mesenchymal transition in head and neck squamous cell carcinoma. Clin Cancer Res 24(3):619–

65 633. PubMed PMID: 29146722. Pubmed Central PMCID: 6171749 Gao YB, Chen ZL, Li JG, Hu XD, Shi XJ, Sun ZM et al (2014) Genetic landscape of esophageal squamous cell carcinoma. Nat Genet. PubMed PMID: 25151357. Epub 2014/08/26. Eng Greenblatt DY, Vaccaro AM, Jaskula-Sztul R, Ning L, Haymart M, Kunnimalaiyaan M et al (2007) Valproic acid activates notch-1 signaling and regulates the neuroendocrine phenotype in carcinoid cancer cells. Oncologist 12(8):942–951. PubMed PMID: 17766653. Epub 2007/09/04. eng Hatch E, Morrow D, Liu W, Cahill PA, Redmond EM (2015) Ethanol inhibits gamma-secretase proteolytic activity in vascular smooth muscle cells. Alcohol Clin Exp Res 39(11):2115–2122. PubMed PMID: 26443551. Pubmed Central PMCID: 4624494. Epub 2015/10/08. eng Kagawa S, Natsuizaka M, Whelan KA, Facompre N, Naganuma S, Ohashi S et  al (2015) Cellular senescence checkpoint function determines differential Notch1-dependent oncogenic and tumor-suppressor activities. Oncogene 34(18):2347–2359. PubMed PMID: 24931169. Pubmed Central PMCID: 4268095 Kang X, Chen K, Li Y, Li J, D'Amico TA, Chen X (2015) Personalized targeted therapy for esophageal squamous cell carcinoma. World J Gastroenterol 21(25):7648–7658. PubMed PMID: 26167067. Pubmed Central PMCID: 4491954 Kasagi Y, Chandramouleeswaran PM, Whelan KA, Tanaka K, Giroux V, Sharma M et  al (2018) The esophageal organoid system reveals functional interplay between Notch and cytokines in reactive epithelial changes. Cell Mol Gastroenterol Hepatol 5(3):333–352. PubMed PMID: 29552622. Pubmed Central PMCID: PMC5852293 Li K, Li Y, Wu W, Gordon WR, Chang DW, Lu M et al (2008) Modulation of notch signaling by antibodies specific for the extracellular negative regulatory region of NOTCH3. J Biol Chem 283(12):8046–8054. PubMed PMID: 18182388 Lin DC, Hao JJ, Nagata Y, Xu L, Shang L, Meng X et al (2014) Genomic and molecular characterization of esophageal squamous cell carcinoma. Nat Genet 46(5):467–473. PubMed PMID: 24686850. Pubmed Central PMCID: 4070589. Epub 2014/04/02. eng Liu T, Zhang X, So CK, Wang S, Wang P, Yan L et  al (2007) Regulation of Cdx2 expression by promoter methylation, and effects of Cdx2 transfection on morphology and gene expression of human esophageal epithelial cells. Carcinogenesis 28(2):488–496. PubMed PMID: 16990345. Epub 2006/09/23. eng Liu Y, Xiong Z, Beasley A, D'Amico T, Chen XL (2016a) Personalized and targeted therapy of esophageal squamous cell carcinoma: an update. Ann N Y Acad Sci 1381(1):66–73. PubMed PMID: 27399176. Pubmed Central PMCID: 5083215 Liu W, Snell JM, Jeck WR, Hoadley KA, Wilkerson MD, Parker JS et  al (2016b) Subtyping sub-Saharan esophageal squamous cell carcinoma by comprehen-

66 sive molecular analysis. JCI Insight 1(16):e88755. PubMed PMID: 27734031. Pubmed Central PMCID: 5053149. Epub 2016/10/14. eng Liu X, Zhang M, Ying S, Zhang C, Lin R, Zheng J et al (2017) Genetic alterations in esophageal tissues from squamous dysplasia to carcinoma. Gastroenterology 153(1):166–177. PubMed PMID: 28365443. Epub 2017/04/04. eng Lobry C, Oh P, Aifantis I (2011) Oncogenic and tumor suppressor functions of Notch in cancer: it's NOTCH what you think. J Exp Med 208(10):1931–1935. PubMed PMID: 21948802. Pubmed Central PMCID: 3182047. Epub 2011/09/29. eng Martincorena I, Fowler JC, Wabik A, Lawson ARJ, Abascal F, Hall MWJ et  al (2018) Somatic mutant clones colonize the human esophagus with age. Science 362(6417):911–917. PubMed PMID: 30337457. Pubmed Central PMCID: PMC6298579 Menke V, van Es JH, de Lau W, van den Born M, Kuipers EJ, Siersema PD et al (2010) Conversion of metaplastic Barrett's epithelium into post-mitotic goblet cells by gamma-secretase inhibition. Dis Model Mech 3(1– 2):104–110. PubMed PMID: 20075383 Meurette O, Mehlen P (2018) Notch signaling in the tumor microenvironment. Cancer Cell 34(4):536–548. PubMed PMID: 30146333 Meyers JM, Spangle JM, Munger K (2013) The human papillomavirus type 8 E6 protein interferes with NOTCH activation during keratinocyte differentiation. J Virol 87(8):4762–4767. PubMed PMID: 23365452. Pubmed Central PMCID: 3624394. Epub 2013/02/01. eng Morrow DJ, Avissar NE, Toia L, Redmond EM, Watson TJ, Jones C et  al (2009) Pathogenesis of Barrett's esophagus: bile acids inhibit the Notch signaling pathway with induction of CDX2 gene expression in human esophageal cells. Surgery 146(4):714–721. discussion 21–2. PubMed PMID: 19789031. Pubmed Central PMCID: PMC3371765 Morrow D, Cullen JP, Liu W, Cahill PA, Redmond EM (2010) Alcohol inhibits smooth muscle cell proliferation via regulation of the Notch signaling pathway. Arterioscler Thromb Vasc Biol 30(12):2597–2603. PubMed PMID: 20930168. Pubmed Central PMCID: 3371770. Epub 2010/10/12. eng Nandagopal N, Santat LA, LeBon L, Sprinzak D, Bronner ME, Elowitz MB (2018) Dynamic ligand discrimination in the Notch signaling pathway. Cell 172(4):869– 80.e19. PubMed PMID: 29398116. Pubmed Central PMCID: 6414217 Natsuizaka M, Whelan KA, Kagawa S, Tanaka K, Giroux V, Chandramouleeswaran PM et  al (2017) Interplay between Notch1 and Notch3 promotes EMT and tumor initiation in squamous cell carcinoma. Nat Commun 8(1):1758. PubMed PMID: 29170450. Pubmed Central PMCID: 5700926 Nowell CS, Radtke F (2017) Notch as a tumour suppressor. Nat Rev Cancer 17(3):145–159. PubMed PMID: 28154375

Y. Li et al. Nyman PE, Buehler D, Lambert PF (2018) Loss of function of canonical notch signaling drives head and neck carcinogenesis. Clin Cancer Res 24(24):6308–6318. PubMed PMID: 30087145. Pubmed Central PMCID: 6295262 Ohashi S, Natsuizaka M, Yashiro-Ohtani Y, Kalman RA, Nakagawa M, Wu L et  al (2010) NOTCH1 and NOTCH3 coordinate esophageal squamous differentiation through a CSL-dependent transcriptional network. Gastroenterology 139(6):2113–2123. PubMed PMID: 20801121. Pubmed Central PMCID: 2997138. Epub 2010/08/31. eng Ohashi S, Natsuizaka M, Naganuma S, Kagawa S, Kimura S, Itoh H et al (2011) A NOTCH3-mediated squamous cell differentiation program limits expansion of EMT-­ competent cells that express the ZEB transcription factors. Cancer Res 71(21):6836–6847. PubMed PMID: 21890822. Pubmed Central PMCID: 3206139. Epub 2011/09/06. eng Okuyama R, Tagami H, Aiba S (2008) Notch signaling: its role in epidermal homeostasis and in the pathogenesis of skin diseases. J Dermatol Sci 49(3):187–194. PubMed PMID: 17624739. Epub 2007/07/13. eng Patel PN, Yu XM, Jaskula-Sztul R, Chen H (2014) Hesperetin activates the Notch1 signaling cascade, causes apoptosis, and induces cellular differentiation in anaplastic thyroid cancer. Ann Surg Oncol 21(Suppl 4):S497–S504. PubMed PMID: 24419754. Pubmed Central PMCID: 4097979. Epub 2014/01/15. eng Pinchot SN, Jaskula-Sztul R, Ning L, Peters NR, Cook MR, Kunnimalaiyaan M et  al (2011) Identification and validation of Notch pathway activating compounds through a novel high-throughput screening method. Cancer 117(7):1386–1398. PubMed PMID: 21425138. Pubmed Central PMCID: 3117093. Epub 2011/03/23. eng Qin HD, Liao XY, Chen YB, Huang SY, Xue WQ, Li FF et  al (2016) Genomic characterization of esophageal squamous cell carcinoma reveals critical genes underlying tumorigenesis and poor prognosis. Am J Hum Genet 98(4):709–727. PubMed PMID: 27058444. Pubmed Central PMCID: 4833434. Epub 2016/04/09. eng Ranganathan P, Weaver KL, Capobianco AJ (2011) Notch signalling in solid tumours: a little bit of everything but not all the time. Nat Rev Cancer 11(5):338–351. PubMed PMID: 21508972. Epub 2011/04/22. eng Restivo G, Nguyen BC, Dziunycz P, Ristorcelli E, Ryan RJ, Ozuysal OY et  al (2011) IRF6 is a mediator of Notch pro-differentiation and tumour suppressive function in keratinocytes. EMBO J 30(22):4571–4585. PubMed PMID: 21909072. Pubmed Central PMCID: 3243593. Epub 2011/09/13. eng Sander GR, Powell BC (2004) Expression of notch receptors and ligands in the adult gut. J Histochem Cytochem 52(4):509–516. PubMed PMID: 15034002 Sawada G, Niida A, Uchi R, Hirata H, Shimamura T, Suzuki Y et al (2016) Genomic landscape of esophageal squamous cell carcinoma in a Japanese popula-

5  NOTCH and ESCC tion. Gastroenterology 150(5):1171–1182. PubMed PMID: 26873401. Epub 2016/02/14. eng Sawangarun W, Mandasari M, Aida J, Morita KI, Kayamori K, Ikeda T et  al (2018) Loss of Notch1 predisposes oro-esophageal epithelium to tumorigenesis. Exp Cell Res 372(2):129–140. PubMed PMID: 30266659 Schneider KJ, Scheer M, Suhr M, Clemens DL (2012) Ethanol administration impairs pancreatic repair after injury. Pancreas 41(8):1272–1279. PubMed PMID: 22617711. Pubmed Central PMCID: 3479327. Epub 2012/05/24. eng Shibata T, Kokubu A, Saito S, Narisawa-Saito M, Sasaki H, Aoyagi K et  al (2011) NRF2 mutation confers malignant potential and resistance to chemoradiation therapy in advanced esophageal squamous cancer. Neoplasia 13(9):864–873. PubMed PMID: 21969819. Pubmed Central PMCID: PMC3182278 Siegel RL, Miller KD, Jemal A (2017) Cancer statistics, 2017. CA Cancer J Clin 67(1):7–30. PubMed PMID: 28055103. Epub 2017/01/06. eng Song Y, Li L, Ou Y, Gao Z, Li E, Li X et  al (2014) Identification of genomic alterations in oesophageal squamous cell cancer. Nature 509(7498):91–95. PubMed PMID: 24670651 Song B, Cui H, Li Y, Cheng C, Yang B, Wang F et  al (2016) Mutually exclusive mutations in NOTCH1 and PIK3CA associated with clinical prognosis and chemotherapy responses of esophageal squamous cell carcinoma in China. Oncotarget 7(3):3599–3613. PubMed PMID: 26528858. Pubmed Central PMCID: 4823130 Steinbuck MP, Winandy S (2018) A review of Notch processing with new insights into ligand-independent notch signaling in T-cells. Front Immunol 9:1230. PubMed PMID: 29910816. Pubmed Central PMCID: 5992298 Sun W, Gaykalova DA, Ochs MF, Mambo E, Arnaoutakis D, Liu Y et al (2014) Activation of the NOTCH pathway in head and neck cancer. Cancer Res 74(4):1091– 1104. PubMed PMID: 24351288. Pubmed Central PMCID: 3944644 Tadeu AM, Horsley V (2013) Notch signaling represses p63 expression in the developing surface ectoderm. Development 140(18):3777–3786. PubMed PMID: 23924630. Pubmed Central PMCID: 3754476. Epub 2013/08/09. eng Tomasetti C, Li L, Vogelstein B (2017a) Stem cell divisions, somatic mutations, cancer etiology, and cancer prevention. Science 355(6331):1330–1334. PubMed PMID: 28336671. Pubmed Central PMCID: PMC5852673 Tomasetti C, Durrett R, Kimmel M, Lambert A, Parmigiani G, Zauber A et al (2017b) Role of stem-cell divisions in cancer risk. Nature 548(7666):E13–EE4. PubMed PMID: 28796214 Tomasetti C, Poling J, Roberts NJ, London NR Jr, Pittman ME, Haffner MC et  al (2019) Cell division rates decrease with age, providing a potential explanation for the age-dependent deceleration in cancer

67 incidence. Proc Natl Acad Sci U S A 116(41):20482– 20488. PubMed PMID: 31548407. Pubmed Central PMCID: PMC6789572 Wakabayashi N, Shin S, Slocum SL, Agoston ES, Wakabayashi J, Kwak MK et  al (2010) Regulation of notch1 signaling by nrf2: implications for tissue regeneration. Sci Signal 3(130):ra52. PubMed PMID: 20628156. Pubmed Central PMCID: 2932745. Epub 2010/07/16. eng Wakabayashi N, Skoko JJ, Chartoumpekis DV, Kimura S, Slocum SL, Noda K et al (2013) Notch-nrf2 axis: regulation of nrf2 gene expression and cytoprotection by notch signaling. Mol Cell Biol 34(4):653–663. PubMed PMID: 24298019. Epub 2013/12/04. eng Wang X, Pasolli HA, Williams T, Fuchs E (2008) AP-2 factors act in concert with Notch to orchestrate terminal differentiation in skin epidermis. J Cell Biol 183(1):37–48. PubMed PMID: 18824566. Pubmed Central PMCID: 2557040. Epub 2008/10/01. eng Wang YC, Wang ZQ, Yuan Y, Ren T, Ni PZ, Chen LQ (2018) Notch signaling pathway is inhibited in the development of Barrett’s esophagus: an in  vivo and in  vitro study. Can J Gastroenterol Hepatol 2018:4149317. PubMed PMID: 29785394. Pubmed Central PMCID: 5892280 Wu S, Powers S, Zhu W, Hannun YA (2016) Substantial contribution of extrinsic risk factors to cancer development. Nature 529(7584):43–47. PubMed PMID: 26675728. Pubmed Central PMCID: PMC4836858 Wyche TP, Dammalapati A, Cho H, Harrison AD, Kwon GS, Chen H et  al (2014) Thiocoraline activates the notch pathway in carcinoids and reduces tumor progression in vivo. Cancer Gene Ther 21(12):518–525. PubMed PMID: 25412645. Pubmed Central PMCID: 4270822. Epub 2014/11/22. eng Xiong Z, Ren S, Chen H, Liu Y, Huang C, Zhang YL et al (2018) PAX9 regulates squamous cell differentiation and carcinogenesis in the oro-oesophageal epithelium. J Pathol 244(2):164–175. PubMed PMID: 29055049. Pubmed Central PMCID: PMC5842438 Ye Q, Jiang J, Zhan G, Yan W, Huang L, Hu Y et al (2016) Small molecule activation of NOTCH signaling inhibits acute myeloid leukemia. Sci Rep 6:26510. PubMed PMID: 27211848. Pubmed Central PMCID: 4876435. Epub 2016/05/24. eng Yizhak K, Aguet F, Kim J, Hess JM, Kubler K, Grimsby J et al (2019) RNA sequence analysis reveals macroscopic somatic clonal expansion across normal tissues. Science 364(6444) PubMed PMID: 31171663 Yokoyama A, Kakiuchi N, Yoshizato T, Nannya Y, Suzuki H, Takeuchi Y et  al (2019) Age-related remodelling of oesophageal epithelia by mutated cancer drivers. Nature 565(7739):312–317. PubMed PMID: 30602793 Yu XM, Phan T, Patel PN, Jaskula-Sztul R, Chen H (2013) Chrysin activates Notch1 signaling and suppresses tumor growth of anaplastic thyroid carcinoma in vitro and in vivo. Cancer 119(4):774–781. PubMed PMID: 22991264. Pubmed Central PMCID: 3528831. Epub 2012/09/20. eng

68 Yuan Y, Tong TJ, Zeng XX, Yang YS, Wang ZQ, Wang YC et al (2017) Longitudinal study of esophageal mucosal damage after esophagectomy and gastric interposition: relationship between reflux-related mucosal injury and Notch signaling. J Thorac Dis 9(12):5249–5260. PubMed PMID: 29312733. Pubmed Central PMCID: 5757047 Zhang L, Zhou Y, Cheng C, Cui H, Cheng L, Kong P et al (2015) Genomic analyses reveal mutational signatures and frequently altered genes in esophageal squamous cell carcinoma. Am J Hum Genet 96(4):597–611. PubMed PMID: 25839328. Pubmed Central PMCID: 4385186. Epub 2015/04/04. eng

Y. Li et al. Zhang Y, Yang Y, Jiang M, Huang SX, Zhang W, Al Alam D et  al (2018) 3D modeling of esophageal development using human PSC-derived basal progenitors reveals a critical role for Notch signaling. Cell Stem Cell 23(4):516–29.e5. PubMed PMID: 30244870. Pubmed Central PMCID: 6282026 Zhong R, Bao R, Faber PW, Bindokas VP, Bechill J, Lingen MW et  al (2015) Notch1 activation or loss promotes HPV-induced oral tumorigenesis. Cancer Res 75(18):3958–3969. PubMed PMID: 26294213. Pubmed Central PMCID: 4573897


Notch Signaling and Liver Cancer Kazunori Kawaguchi and Shuichi Kaneko


cular hepatitis B virus DNA, which regulated cAMP response element-binding protein, thereby affecting Notch1 regulation by the E3 ubiquitin ligase ITCH. This viral pathogenesis in hepatocytes induces liver cancer. In conclusion, Notch signaling exerts various actions and is a clinical signature associated with hepatocarcinogenesis and liver context-related developmental function.

Interactions between liver cells are closely regulated by Notch signaling. Notch signaling has been reported clinically related to bile duct hypogenesis in Alagille syndrome, which is caused by mutations in the Jagged1 gene. Notch activation and hepatocarcinogenesis are closely associated since cancer signaling is affected by the development of liver cells and cancer stem cells. Gene expression and Keywords: genomic analysis using a microarray revealed that abnormalities in Notch-related genes Notch signaling · Liver cancer · were associated with the aggressiveness of Hepatocellular carcinoma · liver cancer. This pattern was also accompaCholangiocarcinoma · Liver cancer stem cells nied with α-fetoprotein- and EpCAM-­ · α-Fetoprotein · Hepatitis B virus · expressing phenotypes in vitro, in vivo, and in Covalently closed circular DNA clinical tissues. Hepatitis B or C virus chronic infection or alcohol- or steatosis-related liver fibrosis induces liver cancer. Previous reports demonstrated that HBx, a hepatitis B virus Notch Signaling and the Liver protein, was associated with Jagged1 expression. We found that the Jagged1 and Notch1 Notch signaling is closely associated with liver signaling pathways were closely associated regeneration because tissue context is more comwith the transcription of covalently closed cir- plex in the liver than in other organs. Hepatocytes develop from hepatoblasts, which are derived from the endoderm, as are bile duct cells. Endothelial and sinusoidal cells are derived from K. Kawaguchi · S. Kaneko (*) the mesoderm, while stellated cells, which are Department of Gastroenterology, Kanazawa located between the hepatic fossa and horizontal University Graduate School of Medical Sciences, septum, are also derived from the mesoderm. Kanazawa, Japan Notch signaling is a cell-to-cell contact signaling e-mail: [email protected] © Springer Nature Switzerland AG 2021 J. Reichrath, S. Reichrath (eds.), Notch Signaling in Embryology and Cancer, Advances in Experimental Medicine and Biology 1287,



system that plays an important role in the liver due to the tissue context-dependent interactions between cells derived from different sources. Abnormalities in Notch signaling in the liver can lead to the development of fatal disorders. Tissue context-related research has been developed in recent years using organoid models, and the generation of a hepatobiliary organoid has been reported (Vyas et  al. 2018). A hepatobiliary-­ pancreatic organoid was also developed recently (Koike et al. 2019). The formation of bile ducts in this organoid was regulated by the gene encoding Hes family bHLH transcription factor 1 (HES1), which is located downstream of the Notch receptor. This phenomenon was dependent on the interactions of different types of neighboring cells via Notch signaling. The relationship between Notch signaling and development has been reported previously and is conserved across animal species (Adams and Jafar-Nejad 2019). Notch signaling is associated with liver homeostasis, and this modulation results in decreased fenestration and increased basement membrane in liver sinusoidal endothelial cells (Duan et  al. 2018; Geisler and Strazzabosco 2015). Moreover, endothelial Notch activation leads to the dedifferentiation of liver sinusoidal endothelial cells and the acceleration of liver fibrogenesis through endothelial nitric oxide synthase-soluble guanylate cyclase signaling and alters the angiocrine profile of liver sinusoidal endothelial cells to compromise hepatocyte proliferation and liver regeneration. A study using zebrafish examining the effects of epigenetic factors on biliary epithelial cell-­ derived hepatocyte progenitor cells (HPCs), which can mediate liver regeneration, reported that a Notch3 mutation led to a severe loss of hepatocytes, which was associated with mainly Sox9b and Cdk8 (Ko et al. 2019). Notch signaling is closely associated with liver fibrosis. Activated hepatic stellate cells, which are a component of the HPC niche, express Jagged1, which plays a central role in the differentiation of HPCs into biliary epithelial cells, and antifibrosis treatment results in HPC-mediated liver regeneration (Kitade et al. 2019).

K. Kawaguchi and S. Kaneko

 lose Relationship Between Notch C Signaling and Liver Diseases Notch signaling has a central role in the formation of different cell types in a context-dependent manner, which underlies the organization of tissues and organs. Abnormalities in Notch signaling are related to diseases that affect the regeneration of specific organs. Alagille syndrome is a congenital disorder of the liver and is related to Notch signaling via mutations in the Jagged1 gene (Oda et al. 1997; McDaniell et al. 2006). However, Notch signaling is also implicated in other liver diseases. Studies of these diseases have enabled the characterization of Notch ligands and receptors, showing that each molecule has a different function, thereby leading to different types of liver pathogenesis (Table 6.1). Notch1 is associated with the tumorigenicity of hepatocytes, and biliary differentiation from HPCs is controlled by autophagy via the Notch1 signaling pathway (Zeng et al. 2016; Wang et al. 2009). M1 macrophages have a role in alcoholic liver injury via Notch1 signaling (Xu et al. 2015). Notch2 is associated with developmental retardation and bile duct development, since defects in Notch2 result in cholangiocyte hypogenesis (Geisler et al. 2008). Notch3 drives the differentiation and progression of cholangiocarcinoma (Guest et  al. 2016). However, the relationship between its activation levels and liver cancer has not been defined, although it is reported to have a role in liver fibrogenesis (Zheng et  al. 2013). Notch3 also induces the commitment of HPCs to the hepatocyte lineage (Ortica et  al. 2014). Notch4 is associated with a reversible arteriovenous malformation, and a deficiency in Notch4 leads to angiogenesis, vascular remodeling, and the generation of hepatocyte lineage HPCs, resulting in regeneration or tumorigenesis (Lu et al. 2016; Carlson et al. 2005; Ahn et al. 2013). The upregulation of Notch1, Notch3, and Notch4 expression is associated with liver cancer involving hepatitis B virus (HBV)-X protein (HBx) (Yang et al. 2017; Carlson et al. 2005). As a Notch ligand, Jagged1 mutations or defects are pathogenic for Alagille syndrome, while Jagged2 is not considered to have an important role in

6  Notch Signaling and Liver Cancer


Table 6.1  Roles of Notch ligands and receptors associated with liver pathogenesis and liver cancer Notch Related functions with liver molecules pathogenesis Jagged1 Mutation: Alagille syndrome Upregulation: HBV cccDNA transcription

Jagged2 DLL1 DLL3 DLL4





NR NR NR Upregulation: liver fibrosis and fat deposition, M1 macrophage activation Downregulation: biliary undifferentiation from HPCs by autophagy Upregulation: HBV cccDNA transcription Upregulation: M1 macrophage activation in alcoholic liver injury Defect: hypogenesis of cholangiocyte Mutation: Alagille syndrome Upregulation: proliferation of hepatoblasts

Upregulation: hepatocytic-­ lineage commitment of HPCs Upregulation: liver fibrogenesis Upregulation: proliferation of hepatoblasts

Reference Oda et al. (1997) Wang et al. (2019)

Reference Gao et al. (2007) Kawaguchi et al. (2016)

Fukuda et al. (2012)

Association with liver cancer Upregulation: HBx and hepatocarcinogenesis Genomic amplification and upregulation: α-fetoprotein-related poor prognosis NR NR NR Upregulation: HBx and hepatocarcinogenesis

Zeng et al. (2016) Wang et al. (2019) Xu et al. (2015)

Upregulation: correlation with β-catenin Upregulation: HBx and hepatocarcinogenesis Upregulation: cancer, poor prognosis

Wang et al. (2009) Kongkavitoon et al. (2016) Ahn et al. (2013)

Geisler et al. (2008) McDaniell et al. (2006) Ortica et al. (2014)

Upregulation: aggressive behavior and immature morphology of liver cancer cells Upregulation: HPCs: dedifferentiated liver cancer Upregulation: relationship with hepatoblastoma Upregulation: differentiation and progression of cholangiocarcinoma

Hayashi et al. (2015) Dill et al. (2013) Jeliazkova et al. (2013) Litten et al. (2011) Guest et al. (2016)

Upregulation: cancer, poor prognosis

Ahn et al. (2013)

Ortica et al. (2014) Zheng et al. (2013) Ortica et al. (2014)

Kongkavitoon et al. (2016)

NR not reported, HPCs hepatocyte progenitor cells, NASH nonalcoholic steatohepatitis

hepatocytes or liver tissue. Although defects in delta-like 1 (DLL1) stimulate neuronal differentiation and severe somite patterning abnormalities, reports on their relationship to the liver are scarce. Moreover, while DLL3 defects produce abnormalities in somitogenesis and autosomal recessive spondylocostal dysostosis, they show little association with liver diseases (Penton et al. 2012). DLL4 defects result in arteriovenous shunting and severe vascular remodeling defects, and upregulated DLL4 expression has been reported in relation to liver diseases such as liver cancer, nonalcoholic steatohepatitis, and HBx-­ related tumorigenesis (Kongkavitoon et al. 2016; Iwamoto et al. 2015; Fukuda and Aikawa 2013; Fukuda et al. 2012). These studies indicated that

Notch-related ligands and receptors have important roles in organ and tissue formation, especially in vascular tissue, bile ducts, and neurons. In patients with chronic HBV infection, the repression of Notch receptors is suggested to repress immune regulation, which results in the inhibition of differentiation and proliferation of effector cells, consequently leading to further pathogenesis (Wei et  al. 2016). Furthermore, fibrosis-related Notch signaling abnormalities in liver diseases are important for liver cancer research because many liver cancers have a background of progressive fibrosis and inflammation, and these microenvironments are closely associated with tumorigenesis and aggressive carcinogenic characteristics. The DLL-Notch pathway is


associated with liver fibrosis (Nakano et al. 2016; Zheng et al. 2016; Bansal et al. 2015).

 lose Relationship Between Notch C Signaling, Liver Cancer Pathogenesis, and Liver Cancer Stem Cells Notch activation and liver carcinogenesis are closely related because cancer signaling is affected by the development of liver cells and the interactions between liver component cells, including bile duct cells, endothelial cells, stellate cells, fibroblasts, and immune cells (Lee et  al. 2016). Notch activation can trigger epithelial-­mesenchymal transformation, promoting the self-renewal of cancer stem cell-like niches in primary tumors (Liu et al. 2018). Some molecules that are affected by Notch signaling have been reported. The pro-oncogenic function of mastermind2 targets genetic alterations in various types of cancer, and it is associated with Notch activation even in hepatobiliary neoplasms (Kochert et  al. 2011; Nemoto et  al. 2007; Lee et  al. 2006). Genetic analysis has shown that mice overexpressing Notch intracellular domain (NICD), which is the active form of Notch1, present with a cluster of liver cancers (Villanueva et al. 2012). Notch2 overexpression causes HPCs to spontaneously develop into dedifferentiated liver cancer cells (Jeliazkova et al. 2013), and Notch-induced malignant hepatocyte transformation is associated with the downregulation of hepatocyte-associated genes, including Sox9 (Liu et al. 2016). Liver cancer has been reported frequently, even among other hepatomas except for hepatocellular carcinoma (HCC). Notch2 is associated with the aggressiveness of HCC and hepatoblastoma (Hayashi et al. 2015; Falix et  al. 2014; Dill et  al. 2013; Litten et al. 2011). RUNX3 is reported to have a role in the suppression of liver cancer and Jagged1 upregulation (Gao et  al. 2010; Nishina et  al. 2011). Jagged1/Notch1 signaling is associated with upstream YAP and Hippo signaling and β-catenin signaling (Wang et al. 2009; Kim et al. 2017). Moreover, gamma secretase inhibitors

K. Kawaguchi and S. Kaneko

(GSIs) are effective angiogenic factors for liver cancer (Yimlamai et  al. 2014; Tschaharganeh et al. 2013; Kim et al. 2017). In the development of cholangiocarcinoma, NICD associated with protein kinase B signaling stimulates the malignant differentiation of hepatocytes (Zhu et al. 2014). Notch contributes to the formation of intrahepatic cholangiocarcinoma (ICC) arising from the conversion of hepatocytes rather than cholangiocytes activated by Notch signaling (Sekiya and Suzuki 2012). This indicates that Notch signaling activates the malignant characteristics of hepatomas and ICC. Liver tumorigenesis caused by HBV is associated with HBx directly or with disease progression (Yang et  al. 2017; Trehanpati et  al. 2012; Gao et  al. 2016; Wang et  al. 2010; Gao et  al. 2007), and the hepatitis C virus core protein is regulated by gamma secretase, which also regulates Notch signaling (Weihofen et  al. 2002; Weihofen et al. 2003). Some liver cancers are associated with angiogenesis, which can be regulated by GSIs, to reduce the development of hepatoma cells, especially α-fetoprotein (AFP)-upregulated cells (Iwamoto et al. 2015). Blocking of Notch signaling molecules, such as with short hairpin RNA (shRNA) targeting Jagged1, results in an effective decrease of AFP-upregulated hepatoma cells (Kawaguchi et al. 2016). Thus, gamma secretase may be a target for liver cancer therapy, although the phenotype might be restricted. Notch signaling is involved in carcinogenesis of the liver from the aspect of cancer stem cells (Lu et al. 2016). The Notch signaling pathway is a crucial determinant of cell fate during development and disease in several organs. In liver cancers, Notch signaling is involved in biliary tree development and tubulogenesis and also has a significant role in the development of HCC and ICC. CD90 is a marker of liver cancer stem cells (LCSCs), and high CD90 expression is reported to correlate with Notch signaling (Luo et  al. 2016). Notch signaling is activated in CD90+ cells, and inhibition of Notch signaling in CD90+ LCSCs decreases tumorigenicity, cell invasion, migration, and the expression of stem cell-related genes. Moreover, cancer stem cell features are

6  Notch Signaling and Liver Cancer

facilitated by stimulating G1-S cell cycle transition and inhibiting Notch signaling-mediated apoptosis. Notch signaling is also important for LCSCs together with Wnt/β-catenin signaling (Wang et al. 2016). Using NOD/SCID mouse models, Notch and Wnt/β-catenin signaling were shown to play important roles in increasing the stemness of LCSCs. The expression of the active form of Notch1 (i.e., NICD) depends on Wnt/β-catenin pathway activation. Moreover, Notch1 negatively contributes to Wnt/β-catenin signaling modulation. The chromatin modification factor lysine-­ specific demethylase 1 (LSD1) is highly expressed in LCSCs in HCC, where its expression is decreased during differentiation (Liu et al. 2018). Notch signaling activates LSD1 through the induction of sirtuin 1, leading to the deacetylation and activation of LSD1 and self-renewal of LCSCs. LSD1 and Notch3 expression is associated with poor patient survival. Other reports demonstrated that inducible nitric oxide synthase promotes the development of CD24+CD133+ LCSCs and is dependent on Notch1 activation (Wang et  al. 2018), which in turn is associated with TACE/ADAM17 activation. Since Notch is cleaved by ADAM family proteins, the progression of LCSCs is closely related to Notch activation and poor survival. Organoid-related research is also an important source of information regarding Notch signaling abnormalities, and liver cancer-initiated organoids can be generated from directly reprogrammed human hepatocytes (Sun et al. 2019). Liver cancer can be induced in this model by inactivating p53 and RB proteins. Using this model, it was demonstrated that the RAS-induced lineage conversion of hepatocytes to intrahepatic cholangiocarcinoma cells can be prevented by the combined inhibition of Notch and JAK-STAT.

J agged1 Gene Abnormalities and Liver Cancer Liver cancer tissue undergoes various genomic changes, and as a Notch-related genomic abnormality, protein O-glucosyltransferase 1 copy


number variation (CNV) is associated with liver cancer (Annani-Akollor et  al. 2014; Thakurdas et  al. 2016). Moreover, we found that the copy number of Jagged1 was increased in liver cancer tissue (Kawaguchi et al. 2016). We analyzed clinical samples and showed that Jagged1 genomic amplification and overexpression in AFP-­ producing cells were associated with liver cancer, the malignant phenotype, and poor overall survival. Specific genes for CNV in liver cancer cells were investigated using microarray-based comparative genomic hybridization (CGH) to determine whether these factors were related to clinical outcome. Chromosome 20p, which includes Jagged1, was found to be amplified in several types of hepatoma cells, and its mRNA was upregulated according to AFP expression levels. We found that Notch signaling inhibition using Jagged1 shRNA and GSIs significantly suppressed the growth of AFP-expressing cells with the suppression of downstream genes. In detail, two GSIs (L-685,458 and N-[N-(3,5-­ difluorophenacetyl-­L-alanyl)]-(S)-phenylglycine t-butyl ester (DAPT)) were used to inhibit the Notch signaling pathway in different hepatoma cell lines. Notch signaling was inhibited in Huh7 and HepG2 cells, which are AFP-expressing cell lines, whereas there was no significant inhibition in the non-AFP-expressing HLE and SKHep1 cell lines (Fig. 6.1a). We assessed the effectiveness of GSIs in epithelial cell adhesion molecule-positive (EpCAM+) cancer stem cells since Notch signaling plays a role in the functions of stem cells and found that EpCAM+ cells were strongly associated with cancer stem cells in hepatomas. The antitumor effect of Notch inhibitors in mouse hepatoma models was assessed. Slower tumor formation was observed after the administration of L-685,458 and DAPT. Examination of the dynamic tumor status of Huh7-implanted NOD-SCID mice treated with GSIs for an extended period of time revealed tumor necrosis and apoptosis (Fig. 6.1b). We found that EpCAM and HES1 staining was weak in the GSI-treated groups except in necrotic areas, suggesting that

K. Kawaguchi and S. Kaneko

74 Relative O.D.

Relative O.D.







*** 0.8

0.8 0.6


0.2 100













Control L-685,458 DAPT

0.6 0.4


0.2 0






0 0


100 m


100 m



Days after GSI administration

** Days after GSI administration







CNV ≥ 1.5 CNV < 1.5


Overall survival (%)


150 hours






Control L-685,458 DAPT

Cumulative survival ratio



1 0.8



0.2 0






Relative O.D.

*** 0.8





Relative O.D.

Cumulative survival ratio



DAPT Duration after surgery (Months)

Patients at risk

CNV ≥ 1.5 CNV < 1.5

C o n tro l




Fig. 6.1 (a) Impact of Notch inhibition on AFP-­ DAB, and cellular nuclei were stained by hematoxylin. producing cells in vitro. Relative cellular growth curve of Scale bars = 100 μm. (c) Cumulative survival rate comhepatoma cell lines after the administration of the pared between GSI- (L-685,458 and DAPT) and control-­ γ-secretase inhibitors L-685,458 and N-[N-(3,5-­ treated NOD-SCID mice implanted with Huh7 cells. The difluorophenacetyl-­L-alanyl)]-(S)-phenylglycine t-butyl survival rates of each of the five samples were compared ester (DAPT). We administered 10  μM of each reagent and calculated using the log-rank t-test. **P